Abstract:
A releasable coupling ( 1 ) comprising a hub ( 3 ) and a shaft ( 5 ), the shaft ( 5 ) being received or receivable in the hub ( 3 ), one of the hub ( 3 ) and shaft ( 5 ) having first ( 54 ) and second ( 55 ) splines, the other of the shaft ( 5 ) and the hub ( 3 ) having corresponding first ( 35 ) and second ( 36 ) rebates in which the first and second splines ( 54, 55 ) are received or are receivable, the first spline ( 54 ) extending to or substantially to a distal end of the said one of the hub ( 3 ) and shaft ( 5 ) and beyond the second spline ( 55 ).

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to a coupling for connecting two rotating members or shafts together. More specifically, although not exclusively, this invention relates to a quick release coupling configured to enable simple and effective releasable engagement between two components. 
       BACKGROUND OF THE INVENTION 
       [0002]    Quick release couplings are well known for a multitude of fields and in a multitude of applications. One exemplary application is in steering wheels, which can mounted on a detachable hub for quick detachment of the steering wheel from the steering column of a vehicle. This arrangement is common in motorsport for narrow-spaced cockpits in order to facilitate the driver climbing in and out. This feature is also used in some vehicles as an anti-theft device. 
         [0003]    This invention is particularly, although not exclusively, directed to releasable couplings for connecting steering wheels to steering columns, but the skilled addressee will appreciate a multitude of other potential applications for the invention. 
         [0004]    Detachable steering wheel arrangements generally include a splined shaft connected to the steering column, which mates with a splined hub connected to the steering wheel. In use, the steering wheel can be positioned so that the hub is aligned with the shaft and pushed over it with the splines of the parts in alignment. The assembly also normally includes a positive lock, for example a ball/detent locking arrangement, which is often actuated by a sleeve. 
         [0005]    Known detachable steering wheel arrangements, and indeed other detachable coupling mechanisms, can be improved to facilitate rapid and easy alignment and connection. 
       OBJECTS OF THE INVENTION 
       [0006]    It is therefore a first non-exclusive object of the invention to provide a releasable coupling arrangement which facilitates rapid and easy alignment and connection. 
         [0007]    It is a further non-exclusive object of the invention to provide a releasable coupling arrangement in which engaging features of the components are protected against damage. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, a first aspect of the invention provides a releasable coupling comprising a hub having a proximal end for attachment to or attached to a site of use and a distal end and a shaft having a proximal end for attachment to or attached to a site of use and a distal end, the shaft being received or receivable in the hub, one of the hub and shaft having first and second splines, the other of the shaft and the hub having corresponding first and second rebates in which the first and second splines are received or are receivable, the first spline extending to or substantially to a distal end of the said one of the hub and shaft and beyond the second spline. 
         [0009]    Advantageously, the first spline of the hub or of the shaft comprises a lead-in portion extending beyond, e.g. axially beyond or further than, the second spline thereof. 
         [0010]    A further aspect of the invention provides a releasable coupling comprising a hub and a shaft, the hub and shaft both comprising distal and proximal ends, the hub comprising first and second splines for engagement with respective first and second splines of or associated with the shaft, the first spline of the wherein the size and/or configuration of the first spline of at least one of the hub and shaft is different to that of the second spline thereof and said lead-in portion extending to the distal end of the hub and/or the proximal end of the shaft. 
         [0011]    The use of splines with different sizes and/or configurations provides a location means for ensuring a pre-determined orientation of the hub relative to the shaft. One of the shaft and hub may have respectively an outer or inner circumferential perimeter, and the first spline, in said circumferential direction, may be larger than the second spline. 
         [0012]    For the avoidance of doubt, the term spline as used herein should be construed broadly. The term may, for example, refer to a projection or key and/or it may refer to a groove or slot or keyway for cooperation with such a projection or key. 
         [0013]    Preferably, the size and/or configuration of the first spline of the hub is different to that of the second spline thereof and/or the size and/or configuration of the first spline of the shaft is different to that of the second spline thereof. Additionally or alternatively, the size and/or configuration of the first spline pair may be different to that of the second spline pair. 
         [0014]    Preferably, the or each of the hub and/or shaft comprises two or more, for example three or more, e.g. a plurality of, second splines or spline pairs. Additionally or alternatively, the or each of the hub and/or shaft may further comprise a third spline, which may comprise the same or substantially the same or a similar or different size and/or configuration than the first and/or second spline or spline pair. 
         [0015]    In one preferred embodiment, one of the hub and shaft comprises a first spline and a plurality of second splines, e.g. wherein each of the second splines comprise the same or substantially the same or a similar size and/or configuration, and the other of said shaft and hub comprises a plurality of second rebates. The shaft may comprise or also comprise a first spline and a plurality of second splines, e.g. wherein each of the second splines comprise the same or substantially the same or a similar size and/or configuration. The first spline of the hub may be configured for engagement with the first spline of the shaft and/or each of the second splines of the hub may be configured for engagement with a respective one of the second splines of the shaft. 
         [0016]    The first spline of the shaft and/or the first spline of the hub is preferably larger, e.g. deeper and/or thicker and/or wider, for example in cross-section, than the second spline or splines thereof. Alternatively, the first spline of the shaft and/or the first spline of the hub may be smaller, e.g. thinner and/or shallower and/or narrower, for example in cross-section, than the second spline or splines thereof. 
         [0017]    A second aspect of the invention provides a releasable coupling comprising a hub and a shaft, the hub comprising first and second splines for engagement with respective first and second splines of or associated with the shaft, wherein the first spline of the hub or of the shaft comprises a lead-in portion extending beyond, e.g. axially beyond or further than, the second spline thereof. 
         [0018]    The lead-in portion may be configured such that when the shaft is inserted into the hub the lead-in portion of the first shaft spline is received within the hub prior to the second shaft spline. 
         [0019]    A third aspect of the invention provides a releasable coupling comprising a hub and a shaft, the hub comprising first and second splines for engagement with respective first and second splines of or associated with the shaft, wherein the first shaft spline comprises a lead-in portion configured such that when the shaft is inserted into the hub the lead-in portion of the first shaft spline is received within the hub prior to the second shaft spline. 
         [0020]    The lead-in portion may be configured such that when the shaft is inserted into the hub one of the splines of the hub contacts the lead-in portion prior to contacting the second shaft spline thereof. 
         [0021]    A fourth aspect of the invention provides a releasable coupling comprising a hub and a shaft, the hub comprising first and second splines for engagement with respective first and second splines of or associated with the shaft, wherein the first spline of the shaft comprises a lead-in portion extending to or towards a distal end of the shaft and configured such that when the shaft is inserted into the hub one of the splines of the hub contacts the lead-in portion prior to contacting the second shaft spline thereof. 
         [0022]    A fifth aspect of the invention provides a releasable coupling comprising a hub and a shaft, the hub comprising first and second splines for engagement with respective first and second splines of or associated with the shaft, wherein the first spline of the hub comprises a lead-in portion configured such that when the shaft is inserted into the hub one of the splines of the shaft contacts the lead-in portion prior to contacting the second shaft spline thereof. 
         [0023]    The provision of a lead-in portion ensures that one of the splines engages before the other(s). This facilitates a smooth insertion of the shaft into the hub and reduces the likelihood of damage to the other spline(s). 
         [0024]    For the avoidance of doubt, any of the features described herein apply equally to any aspect of the invention. 
         [0025]    At least one, preferably both, of the first and second splines of the shaft may comprise a key and/or at least one, preferably both, of the first and second splines of the hub may comprise a keyway. Alternatively, at least one, e.g. both, of the first and second splines of the shaft may comprise a keyway and/or at least one, e.g. both, of the first and second splines of the hub may comprise a key. The splines of the shaft may be included on an external, e.g. circumferential, surface thereof and/or the splines of the hub may be included on an internal, e.g. circumferential, surface thereof. 
         [0026]    Preferably, each of the hub and shaft comprise a plurality of interengaging splines or keys, for example projecting splines or keys, e.g. wherein the spaces between adjacent splines or keys receive, or provide keyways or rebates for the splines of the other of the hub and shaft. 
         [0027]    One or more of the first and/or second splines may comprise a lead-in taper, for example to facilitate engagement. Preferably, the lead-in taper of the first spline, or of the lead-in portion of the first spline, is more gradual or less acute than the lead-in taper of the second spline or splines. In some embodiments, the lead-in taper of the first spline, or of the lead-in portion of the first spline, is between 5° and 60°, for example between 10° and 50°, e.g. between 20° and 40°, preferably between 25° and 35°, more preferably between 30° and 32°, such as approximately 31°. 
         [0028]    Additionally or alternatively, the lead-in taper of the second spline may be between 10° and 80°, for example between 20° and 70°, e.g. between 30° and 60°, preferably between 40° and 50°, more preferably between 44° and 46°, such as approximately 45°. 
         [0029]    The hub may comprise a lead-in or lead-in portion or sleeve, which may be free of splines and/or rebates and/or comprise a substantially cylindrical surface that may be smooth. 
         [0030]    The lead-in or lead-in portion or sleeve may be configured to guide the shaft, for example prior to engagement of the first and/or second splines or spline pairs. 
         [0031]    The coupling may further comprise a lock or lock means, for example a releasable lock or lock means. The lock or lock means may comprise an interference fit and/or snap fit arrangement. Additionally or alternatively, the lock or lock means may comprise a projection that is at least partially receivable, e.g. releasably receivable, in or by and/or engageable, e.g. releasably engageable, with a recess or depression or detent. Additionally or alternatively, the lock or lock means may comprise a sleeve extending around the shaft and hub when said shaft has been received in said hub. 
         [0032]    The projection may be biased toward a deployed or projecting or projected or engaging or engaged position or condition, for example such that when the projection is aligned with the recess or depression or detent it is at least partially biased therein and/or into engagement therewith. Alternatively, the projection may be biased toward a retracted position or condition. In some embodiments, the projection comprises a ball, for example a biased or resiliently biased or sprung ball, e.g. that is retained within one of the hub or shaft. 
         [0033]    In some embodiments, the hub comprises the projection or ball and/or the shaft comprises the recess or depression or detent. In an alternative embodiment, the shaft comprises the projection or ball and/or the hub comprises the recess or depression or detent. 
         [0034]    Preferably, the coupling further comprises a lock sleeve that is movable or translatable along the coupling or hub or shaft and/or that surrounds or receives at least a portion of the coupling or hub or shaft. The lock sleeve is preferably operable or movable or translatable between a first position or condition, for example in which the shaft may be removed from the hub and/or in which the projection or ball is in, or able to be urged to, a retracted position or condition, and a second position or condition, for example in which the shaft is inhibited or prevented from being removed from the hub and/or in which the projection or ball is deployed. 
         [0035]    In some embodiments, the lock sleeve comprises the projection or ball or actuates or operates or biases the projection or ball, e.g. to or toward the deployed or projecting or projected or engaging or engaged position or condition. In other embodiments, the lock sleeve comprises the recess or depression or detent. 
         [0036]    Further aspects of the invention provide a shaft as described above and/or a hub as described above, e.g. for use in a releasable coupling as described above. The hub may further comprise the lock sleeve and/or the ball. 
         [0037]    A further aspect of the invention provides a quick release or detachment mechanism, e.g. for a steering wheel, the mechanism comprising a releasable coupling as described above. 
         [0038]    A yet further aspect of the invention provides a steering wheel comprising a hub as described above or a shaft as described above. 
         [0039]    A yet further aspect of the invention provides a steering column comprising a shaft as described above. 
         [0040]    A yet further aspect of the invention provides a steering column or steering column shaft comprising a shaft as described above. 
         [0041]    A yet further aspect of the invention provides a kit of parts for assembly into a coupling or quick release or detachment mechanism as described above. The kit may comprise a hub as describe above and/or a shaft as described above and/or a steering wheel and, preferably, locking means to releasably secure the hub to the shaft in use. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0042]    Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: 
           [0043]      FIG. 1  is an exploded front perspective view of a steering wheel and part steering column shaft incorporating a coupling according to one embodiment of the invention; 
           [0044]      FIG. 2  is a rear perspective view of the steering wheel and part steering column shaft of  FIG. 1  shown in an assembled condition; 
           [0045]      FIG. 3  is a perspective partial section view of the coupling of the assembly of  FIGS. 1 and 2  illustrating the mating components of the hub and shaft; 
           [0046]      FIG. 4  is an enlarged view of the mating components shown in  FIG. 3 ; 
           [0047]      FIG. 5  is a perspective view of the part shaft of  FIG. 1  prior to cutting of the splines; 
           [0048]      FIG. 6  is an enlarged view of the first spline of the shaft of the assembly of  FIGS. 1 to 4 ; 
           [0049]      FIG. 7  is a side view of the part shaft of  FIG. 1 ; and 
           [0050]      FIG. 8  is a section view along line A-A of  FIG. 7 . 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0051]    Referring now to the Figures, there is shown a steering wheel assembly  1  incorporating a releasable coupling according to one embodiment of the invention. The assembly  1  includes a steering wheel  2 , a hub  3  for attachment to the steering wheel  2 , a lock sleeve  4  and a shaft  5 . The hub  3  having a proximal end  3   a  and a distal end  3   b,  the shaft  5  having a proximal end  5   a  and a distal end  5   b.  The steering wheel  2  is of a standard design and includes a wheel hub  20  with three fixing holes  21  for receiving fasteners (not shown). 
         [0052]    The hub  3  includes a triangular mounting flange  30  at a first of its ends with mounting holes  30   a  adjacent each of the corners of the flange  30  for cooperation to the three fixing holes  21  of the wheel  2 , wherein fasteners (not shown) engage the holes  21 ,  30   a  to secure the hub  3  to the wheel  2 . The hub  3  also includes a tubular body  31  with a pair of ridges  32  on its outer circumferential surface, an axial hole  33  adjacent its second end and a plurality of splines  34 ,  35 ,  36  extending radially from the inner surface of the body  31 . The splines  34 ,  35 ,  36  include a plurality of keys  34  with lead-in tapers  34   a  and define a first keyway  35  and a plurality of second keyways  36 . The first keyway  35  is wider than the second keyways  36 . The body  31  of the hub  3  also includes lead-in sleeve  37 , which is free of splines and includes a smooth cylindrical internal surface  37   a.  The hub  3  includes a ball (not shown) captivated within the axial hole  33  by opposed lips (not shown). 
         [0053]    The lock sleeve  4  includes an actuating flange  40  and a tubular body  41  with an inwardly extending radial ridge  42  on its internal circumferential surface  43 . In an assembled condition, the lock sleeve  4  is mounted over the body  31  of the hub  3  and able to translate along it, but wherein such translation is limited by the ridges  32  of the body  31  of the hub  3 . The assembly also includes a compression spring (not shown) captivated between the ridge  42  and the hub  3 , which biases the lock sleeve  4  toward the second end of the hub  3 . 
         [0054]    At rest, the radial ridge  42  of the lock sleeve  4  urges the captivated ball (not shown) into a deployed position in which it projects from the internal surface  37   a  of the lead-in sleeve  37  of the hub  3 . Actuation of the flange  40  of the lock sleeve  4  causes it to translate along the hub  3 , bringing the ridge  42  out of alignment with the ball (not shown) and allowing the ball (not shown) to be urged into the axial hole  33 . 
         [0055]    The part shaft  5  includes an axial hole  50 , a base circumferential diameter  51 , an intermediate diameter  52  and a shaft diameter  53 , shown more clearly in  FIG. 5 . Adjacent the free end of the part shaft  5  there are a plurality of splines  54 ,  55  projecting radially outwardly from the base diameter  51  and terminating at the intermediate diameter  52 . The splines  54 ,  55  include a first spline or key  54  and a plurality of second splines or keys  55 . The first spline or key  54  is wider than the second splines or keys  55  and includes a lead-in portion  56  with a taper beginning at the free end of the part shaft  5  and extending at a first lead-in angle ø, which is 31° in this embodiment. The second splines or keys  55  also include lead-in tapers  55   a  that begin downstream and spaced from the free end of the part shaft  5  and extend at a second lead-in angle α that is more acute than the first lead-in angle, namely 45° in this embodiment. 
         [0056]    The part shaft  5  also includes a locking portion  57  downstream and spaced from the splines  54 ,  55 . The circumferential surface of the locking portion  57  also corresponds to the intermediate diameter  52  and includes a locking groove  58  extending about its circumference for receiving the ball (not shown) captivated in the axial hole  33  of the hub  3  when it is in the deployed position. 
         [0057]    In use, the flange  40  of the lock sleeve  4  is urged toward the steering wheel  2  to bring the ridge  42  out of alignment with the ball (not shown) and allow the ball (not shown) to move within the axial hole  33 . With the lock sleeve  4  actuated, the hub  3  is placed over the part shaft  5  and pushed thereon such that the splines  54 ,  55  enter the lead-in portion  36  of the hub  3  until the lead-in portion  56  of the first spline  54  abuts lead-in tapers  34   a  of the second splines  34 . The steering wheel  2  is then rotated while urging the hub  3  gently against the shaft  5  until the first spline  54  aligns with the first keyway  35 . 
         [0058]    At this point, the shaft  5  is inserted further into the hub  3  with the first spline  54  sliding within the first keyway  35  and the second splines  55  sliding within the second keyways  36  until the free end of the hub  3  comes into contact with the shaft diameter  53 , thereby preventing any further movement. The lock sleeve  4  is then released, thereby urging the ball (not shown) into the deployed position and securing the steering wheel axially onto the shaft  5 . 
         [0059]    An alternative to tapering the first spline or key  54  in the manner shown in the Figures (and described above) is to gradually narrow the width of said first spline or key  54  in a circumferential direction, beginning downstream, such that the lead-in portion  56  is provided with a pointed, upstanding end. However, and although not excluded from the or scope of this invention, we believe that tapering the first spline or key  54  in the manner shown in the Figures is advantageous over this narrowing. 
         [0060]    Firstly, during misaligned coupling or attempted coupling, where the lead-in portion  56  of the first spline or key  54  of the part shaft  5  contacts the lead-in taper  34   a  of splines  34  of the hub  3 , the contact area will be greatly reduced for a narrowed rather than a tapered lead-in portion  56 . As a consequence, for the same applied force, the pressure exerted on the end of the lead-in portion  56  (and to the part or parts of the end of the spline(s)  34  to which it contacts) will be substantially lower using a relatively broad rather than a relatively narrow lead-in portion  56 . Therefore, the likelihood of fracture, distortion and/or other forms of damage to the splines  54 ,  34  is reduced by having a broad rather than a narrow leading spline. 
         [0061]    Secondly, by maintaining the width of the lead-in portion  56  by tapering (as opposed to a pointed end to lead-in portion  56  as produced by narrowing) the likelihood of said lead-in portion  56  contacting multiple splines  34  during misaligned connection is increased. Advantageously, this makes it highly unlikely that during misaligned connection the lead-in portion  56  of the first spline or key  54  will become accidentally incorrectly engaged in keyways  35  between splines  34  of the hub  3 . A pointed end to the lead-in portion  56  would greatly increase the likelihood of accidental incorrect engagement in keyways  35  between splines  34  of the hub  3 , and could therefore lead to the part shaft  5  and hub  3  becoming wedged relative to each other in a misaligned position. 
         [0062]    In order to remove the steering wheel  2 , the lock sleeve  4  is depressed and the steering wheel  2  and hub  3  is pulled to separate them from the shaft  5 . 
         [0063]    It will be appreciated by those skilled in the art that several variations to the aforementioned embodiments are envisaged without departing from the scope of the invention. For example, the first spline  54  and/or the first keyway  35  may have the same width, but a different depth and/or a completely different shape or configuration to the second splines  55  and/or second keyway  36 . Alternatively, the first spline  54  and/or the first keyway  35  need not be of a different size and configuration to the second splines  55  and/or second keyways  36 . Additionally or alternatively, the keys  54 ,  55 ,  34  and keyways  35 ,  36  may be replaced with other spline configurations. 
         [0064]    The or each of the hub  3  and/or shaft  5  may include a third spline and/or key and/or keyway, which may have a different size and/or configuration than the first and/or second splines  54 ,  55  and/or than the first and/or second keyways  35 ,  36 . The angle of the lead-in tapers  34   a  of the second splines  34  need not be more acute than that of the lead-in portion  56  of the first spline  54 . 
         [0065]    Additionally or alternatively, the hub  3  need not include a lead-in sleeve  37  and/or the coupling need not include a ball (not shown) and groove  58  arrangement or a lock sleeve  4 . It will be appreciated that either of these elements may be omitted or replaced with other equivalent features. Alternatively, the ball (not shown) may be sprung to either the deployed or retracted position or condition. 
         [0066]    The coupling may be configured in reverse, e.g. wherein the shaft  5  may include the first keyway  35  and the hub  3  may include the first spline  54 . In some embodiments, the shaft  5  may comprise the ball (not shown) and/or the hub  3  may comprise the groove  58 . 
         [0067]    The assembly  1  may be provided in kit form, for example the shaft  5  of a vehicle may be configured or adapted to receive a hub  3  according to the invention, wherein one or more components, e.g. the steering wheel  2  and/or the hub  3  and/or the lock sleeve  4  may be sold together or separately, either assembled or in kit form. 
         [0068]    It will also be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.