Abstract:
A telescopic wand for a vacuum cleaner includes an inner tube, an outer tube, and a catch, wherein the inner tube includes multiple projections, the outer tube includes a pair of bosses, and the catch includes a locking stub. The catch pivotally attaches to the outer tube and pivots between lock and unlock positions. The locking stub projects between two of the projections in the lock position and is lifted clear of the projections in the unlock position. Applying a push or pull force to the wand when in the locked position causes a first projection to abut a side of the locking stub and the bosses to abut an opposite side thereof, and applying the push or pull force to the wand when in the unlock position causes the inner tube to slide relative to the outer tube and the second projection to pass between the bosses.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to United Kingdom Application No. 1519658.7, filed Nov. 6, 2015, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a telescopic wand for a vacuum cleaner. 
       BACKGROUND OF THE INVENTION 
       [0003]    The telescopic wand of a vacuum cleaner may comprise an inner tube, an outer tube, and a catch for locking the position of the inner tube relative to the outer tube. The catch may be pivotally attached to the outer tube for movement between a lock position and an unlock position. When the catch is in the lock position, push and pull forces applied to the wand must be borne by the pivot. However, the applied force can be significant and thus the required pivot may compromise the size and/or the assembly of the wand. Additionally, depending on the location of the pivot, the catch may pivot downwards or upwards in response to the applied force. With sufficient applied force, the catch may jam in the lock position or pivot to the unlock position. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a telescopic wand for a vacuum cleaner, the wand comprising an inner tube, an outer tube, and a catch, wherein: the inner tube comprises a plurality of projections, the outer tube comprises a pair of bosses, and the catch comprises a locking stub; the catch is pivotally attached to the outer tube and pivots between a lock position and an unlock position; the locking stub projects into a recess between two of the projections when the catch is in the lock position, and the locking stub is lifted clear of the projections when the catch is in the unlock position; applying a push or pull force to the wand when the catch is in the lock position causes a first of the two projections to abut a side of the locking stub and the bosses to abut an opposite side of the locking stub; and applying the push or pull force to the wand when the catch is in the unlock position causes the inner tube to slide relative to the outer tube and a second of the two projections to pass between the bosses. 
         [0005]    Consequently, when the catch is in the lock position and a push or pull force is applied to the wand, the force of the first projection on the catch is opposed by the bosses. The pivot between the catch and the outer tube is not therefore required to bear the full magnitude of the applied force. As a result, a smaller pivot may be employed that would otherwise yield if subjected to the full magnitude of the applied force. 
         [0006]    When the catch is in the unlock position and the push or pull force is applied to the wand, the inner tube slides relative to the outer tube and the second of the two projections passes between the bosses. By having an arrangement in which the second projection passes between the bosses, it is possible to locate the bosses at a similar height to that of the first projection. This then has the benefit that, when the catch is in the lock position and a push or pull force is applied to the wand, the force applied by the bosses to the catch may have a similar line of action to that applied by the first projection. As a result, the catch experiences less torque and is therefore less likely to pivot when the push or pull force is applied. 
         [0007]    The inner tube may comprise a flat section from which the projections project, and the flat section may be wider than the projections such that the flat section extends along either side of each projection. This then has the benefit that the bosses of the outer tube may be located at the same or a similar height as the projections in a relatively compact manner In particular, the outer tube may have an inner diameter that is only slightly larger than the outer diameter of the inner tube so as to permit sliding movement. The flat surface of the inner tube then provides the space for the bosses of the outer tube. 
         [0008]    The inner tube may have a cross-sectional shape corresponding to a major segment of a circle or oval, and the flat surface may correspond to the chord of the major segment. Furthermore, the outer tube may have a cross-sectional shape that is circular or oval. 
         [0009]    The catch may pivot about a pivot point that is located above the projections. This then has the advantage that a relatively compact catch may be employed. In the absence of the bosses, a moment of force or torque may be exerted on the catch in response to the push or pull force. This torque would then cause the catch to pivot downwards or upwards, which may cause the catch to jam in the lock position or move to the unlock position. By employing an arrangement in which the second projection passes between the bosses, the net force applied by the bosses may have a similar line of action to that applied by the first projection. As a result, the catch experiences less torque in response to the applied force. It is therefore possible to locate the pivot point above the projections without fear of the catch becoming jammed in the lock position or moving to the unlock position. 
         [0010]    The outer tube may comprise a pair of further bosses. Applying a push force to the wand when the catch is in the lock position then causes the first projection to abut the side of the locking stub and the bosses to abut the opposite side of the locking stub. Furthermore, applying a pull force to the wand when the catch is in the lock position causes the second projection to abut the opposite side of the locking stub and the further bosses to abut the side of the locking stub. As a result, the pivot between the catch and the outer tube is not required to bear either a push force or a pull force. 
         [0011]    When the catch is in the unlock position and the push or pull force is applied to the wand, the inner tube may slide relative to the outer tube and the first projection may pass between the further bosses. By having an arrangement in which the first projection passes between the further bosses, it is possible to locate the further bosses at a similar height to that of the second projection. This then has the benefit that, when the catch is in the lock position and a pull force is applied to the wand, the force applied by the further bosses to the catch may have a similar line of action to that applied by the second projection. As a result, the catch experiences less torque and is therefore less likely to move inadvertently to the unlock position when the pull force is applied. 
         [0012]    When the catch is in the lock position and the push or pull force is applied to the wand, the first projection may be said to apply a first force to the locking stub and the bosses may be said to apply a second force to the locking stub. The second force may then be equal and opposite to the first force and have the same line of action as the first force. As a result, the pivot is not required to bear any of the applied force. Moreover, no torque is exerted on the catch and thus the catch does not pivot in response to the applied force. 
         [0013]    The present invention also provides a telescopic wand for a vacuum cleaner, the wand comprising an inner tube, an outer tube, and a catch, wherein: the inner tube comprises a plurality of projections, the outer tube comprises a pair of bosses, and the catch comprises a locking stub; the catch is pivotally attached to the outer tube and pivots between a lock position and an unlock position; the locking stub projects into a recess between two of the projections when the catch is in the lock position, and the locking stub is lifted clear of the projections when the catch is in the unlock position; applying a push or pull force to the wand when the catch is in the lock position causes a first of the two projections to apply a first force to the locking stub and the bosses to apply a second force to the locking stub, the second force being equal and opposite to the first force and having the same line of action as the first force. 
         [0014]    Since the bosses apply a force to the locking stub that is equal and opposite to and has the same line of action as the force applied by the first projection, the pivot between the catch and the outer tube is not required to bear the push or pull force. It is therefore possible to employ a pivot that would otherwise yield if subjected to the push or pull force. Moreover, since the forces applied by the bosses and the first projection have the same line of action, no torque is exerted on the catch as a result of the push or pull force and thus inadvertent pivoting of the catch may be avoided. 
         [0015]    The outer tube may comprise a pair of further bosses. Applying a push force to the wand when the catch is in the lock position then causes the first of the two projections to apply the first force to the locking stub. Furthermore, applying a pull force to the wand when the catch is in the lock position causes a second of the two projections to apply a third force to the locking stub and the further bosses to apply a fourth force to the locking stub. The fourth force may then be equal and opposite to the third force and have the same line of action as the third force. As a result, the pivot between the catch and the outer tube is not required to bear either a push force or a pull force, and no torque is exerted on the catch as a result of the push or pull force. 
         [0016]    In the present description, the terms ‘upward’, ‘downward’, ‘above’ and ‘below’ are made with reference to the central longitudinal axis of the tubes. Consequently, the terms ‘upward’ and ‘downward’ should be understood to mean in directions away from and towards the longitudinal axis. Furthermore, where a first feature is described as being located ‘above’ or ‘below’ a second feature, this should be understood to mean that the first feature is located further from or closer to the longitudinal axis. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    In order that the present invention may be more readily understood, an embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0018]      FIG. 1  is a perspective view of a telescopic wand in accordance with the present invention; 
           [0019]      FIG. 2  is a partially exploded view of the telescopic wand; 
           [0020]      FIG. 3  is a perspective view of a section through the telescopic wand; 
           [0021]      FIG. 4  is the same view as  FIG. 3  but with a catch of the telescopic wand omitted in order to better illustrate certain features of the wand; 
           [0022]      FIG. 5  is a side view of a sectional slice through the telescopic wand with the catch in a lock position; 
           [0023]      FIG. 6  is the same view as  FIG. 5  but with the catch in an unlock position; 
           [0024]      FIG. 7  is a plan view of the section illustrated in  FIG. 3 ; and 
           [0025]      FIG. 8  is an enlarged view of the boxed area of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    The telescopic wand  1  of  FIGS. 1 to 8  comprises an inner tube  2 , an outer tube  3 , and a catch assembly  4 . 
         [0027]    The inner tube  2  is roughly cylindrical in shape. However, the top of the tube  2  comprises a flat section  20 . As a result, the inner tube has a cross-sectional shape that resembles the major segment of a circle, with the chord of the segment defining the flat section  20 . The inner tube  2  comprises a plurality of projections  21  that project upwardly from the flat section  20 . The gap between each pair of projections  21  defines a recess  22  into which a locking stub  44  of the catch assembly  4  projects; this is described below in more detail. A first end of the inner tube  2  is attachable to a cleaner head or accessory (not shown), and a second opposite end of the inner tube  2  is received within the outer tube  3 . The inner tube  2  slides relative to the outer tube  3  along a central longitudinal axis  23 , and a seal  24  is provided at the second end of the inner tube  2  so as to minimise leaks between the inner tube  2  and the outer tube  3 . 
         [0028]    The outer tube  3  is cylindrical in shape. A first end of the outer tube  3  surrounds the inner tube  2 , and a second opposite end is attachable to a handle or hose (not shown). An opening  31  is formed in the top of the outer tube  3  and is located towards the first end of the tube  3 . The outer tube  3  comprises a pair of lugs  32  located on opposite sides of the opening  31 , and a stop  33  located at one end of the opening  31 . As explained below, the lugs  32  act as fulcrums for the catch assembly  4 , whilst the stop  33  acts to limit movement of the catch assembly  4 . The outer tube  3  further comprises a pair of front bosses  34  and a pair of rear bosses  35 . The front bosses  34  are located in front of the locking stub  44  of the catch assembly  4 , and the rear bosses  35  are located behind the locking stub  44 . The bosses  34 , 35  are located approximately at the same height as that of the projections  21 . Furthermore, the bosses of each pair  34 , 35  are located on opposite sides of the projections  21 . Consequently, when the inner tube  2  slides relative to the outer tube  3 , the projections  21  passes between the front bosses  34  and between the rear bosses  35 . As explained below, when a push or pull force is applied to the wand  1 , the bosses  34 , 35  act to oppose the force applied by the projections  21  to the locking stub  44 . 
         [0029]    The catch assembly  4  comprises a catch  41  and a spring  42 . 
         [0030]    The catch  41  is a unitary body that comprises a button  43  and a locking stub  44 . The catch  41  is pivotally mounted to the outer tube  3  at a pivot point  45  located between the button  43  and the locking stub  44 . More particularly, the catch  41  comprises a pair of recesses  46  located on opposite sides of the catch  41 . The lugs  32  of the outer tube  3 , which are roughly triangular in shape, are seated in the recesses  46  and act as fulcrums for the catch  41 . 
         [0031]    The spring  42  is a leaf spring that is secured at one end to the underside of the catch  41  and at the opposite end to the inside of the outer tube  3 . The spring  42  applies a biasing force to the catch that pulls the locking stub  44  downwards towards the inner tube  2 . 
         [0032]    The catch  41  pivots between a lock position ( FIG. 5 ) and an unlock position ( FIG. 6 ). The catch  41  is biased by the spring  42  to the lock position. When the catch  41  is in the lock position, the locking stub  44  projects into a recess  22  between two of the projections  21  of the inner tube  2 . Movement of the inner tube  2  relative to the outer tube  3  is then prevented. In particular, when the inner tube  2  is moved to the left or right, the locking stub  44  abuts one of the projections  21  so as to prevent any further movement. The catch  41  is moved to the unlock position by depressing the button  43 . When the button  43  is depressed, the catch  41  pivots about the pivot point  45  against the biasing force of the spring  42 . As a result, the locking stub  44  pivots upwards. The locking stub  44  is then lifted clear of the recess  22  and the projections  21 . The inner tube  2  is then free to slide left and right relative to the outer tube  3 . When the button  43  is released, the spring  42  biases the locking stub  44  downwards. Depending on the position of the inner tube  2 , the locking stub  44  is biased down into one of the recesses  22  or onto one of the projections  21 . In the former case, the catch  41  is returned to the lock position. In the latter case, further movement of the inner tube  2  causes the locking stub  44  to slide on top of the projection  21  until such time as the locking stub  44  aligns with and snaps into one of the recesses  22 , at which point the catch  41  is returned to the lock position. 
         [0033]    As can be seen in  FIGS. 5 and 6 , the stop  33  of the outer tube  3  limits both the upward and downward movement of the catch  41 . When the button  43  is depressed and the locking stub  44  pivots upwards, the locking stub  44  abuts the underside of the stop  33  when the locking stub  44  is clear of the projections  21 . Further downward travel of the button  43  is therefore prevented and thus the user is provided with an indication that the catch  41  is in the unlock position. When the button  43  is released and the spring  42  biases the locking stub  44  downwards, the catch  41  abuts the top of the stop  33  when the catch  41  is level with the outer tube  3 . Consequently, although the locking stub  44  projects into the recess  22  when the catch  41  is in the lock position, there is nevertheless a small clearance between the bottom of the locking stub  44  and the top of the inner tube  2 . By stopping the catch  41  at a position level with the outer tube  3 , the catch  41  is flush with the outer tube  3  when in the lock position. This then has the advantage that the catch  41  does not inadvertently snag on items, such as upholstery or curtains, during use. 
         [0034]    A more detailed description will now be provided of the interactions that occur between the catch  41 , the inner tube  2  and the outer tube  3  when the catch  41  is in the lock position and a push or pull force is applied to the wand  1 . A push or pull force is one that encourages the inner tube  2  to move relative to the outer tube  3  along the longitudinal axis  23 . A push force then acts in a direction that encourages the inner tube  2  to move towards the outer tube  3 , whilst a pull force acts in a direction that encourages the inner tube  2  to move away from the outer tube  3 . So when the catch  41  is in the unlock position and a push force is applied to the wand  1 , the inner tube  2  and the outer tube  3  are brought together and the length of the wand  1  contracts. Conversely, when the catch  41  is in the unlock position and a pull force is applied to the wand  1 , the inner tube  2  and the outer tube  3  separate and the length of the wand  1  expands. 
         [0035]      FIGS. 7 and 8  illustrate the wand  1  with the catch  41  in the lock position. The locking stub  44  projects into a recess  22  between a first projection  21   a  and a second projection  21   b  of the inner tube  2 . 
         [0036]    When a push force is applied to the wand  1 , the inner tube  2  moves relative to the outer tube  3  and the catch  41  in a direction towards the right. The first projection  21   a  then abuts a first side  47  of the locking stub  44  and applies a first force to the locking stub  44 . There is a degree of play in the pivot between the catch  41  and the outer tube  3 ; that is to say that the catch  41  is free to move relative to the outer tube  3  to the left and right by a small amount before the lugs  32  of the outer tube  3  engage with the walls of the recesses  46  in the catch  41  (see  FIG. 7 ). Consequently, in response to the first force, the catch  41  moves relative to the outer tube  3  in a direction towards the right. The rear bosses  35  then abut a second opposite side  48  of the locking stub  44  and apply a second force to the locking stub  44 . The second force is equal and opposite to the first force and has the same line of action as the first force. As a result, further movement of the inner tube  2  to the right is prevented. 
         [0037]    When a pull force is applied to the wand  1 , the inner tube  2  moves relative to the outer tube  3  and the catch  41  in a direction towards the left. The second projection  21   b  then abuts the second side  48  of the locking stub  44  and applies a third force to the locking stub  44 . Owing to the degree of play in the pivot between the catch  41  and the outer tube  3 , the third force causes the catch  41  to move relative to the outer tube  3  in a direction towards the left. The front bosses  34  then abut the first side  47  of the locking stub  44  and apply a fourth force to the locking stub  44 . The fourth force is equal and opposite to the third force, and has the same line of action as the third force. As a result, further movement of the inner tube  2  to the left is prevented. 
         [0038]    Irrespective of whether a push force or a pull force is applied to the wand  1 , the bosses  34 , 35  apply a force to the locking stub  44  that is equal and opposite to and has the same line of action as the force applied by the projection  21  of the inner tube  2 . As a result, the pivot between the catch  41  and the outer tube  3  is not required to bear the push or pull force. It is therefore possible to employ a pivot that would otherwise yield if subjected to the push force or pull force. 
         [0039]    The bosses  34 , 35  apply a force having the same line of action as that applied by the projection  21 . This is made possible by locating the bosses  34 , 35  on opposite sides of the projection  21  at approximately the same height as the projection  21 . As a consequence of locating the bosses  34 , 35  in this manner, the projections  21  pass between the bosses  34 , 35  when the catch  41  is in the unlock position and a push or pull force is applied to the wand  1 . 
         [0040]    The catch  41  pivots relative to the outer tube  3  at a point  45  that is located above the projections  21 . Consequently, if the bosses  34 , 35  were omitted and the pivot were designed to withstand the applied force, the force applied to the catch  41  by the outer tube  3  would have a different line of action to that applied to the catch  41  by the projections  21 . In particular, the force applied by the outer tube  3  would have a higher line of action. As a result, a moment of force or torque would be exerted on the catch  41 . This torque would cause the locking stub  44  to pivot downwards or upwards depending on whether the applied force is a push force or a pull force. The stop  33  of the outer tube  3  would prevent the locking stub  44  from pivoting downwards. However, the locking stub  44  may pivot upwards against the biasing force of the spring  42 . If the force applied to the wand  1  were sufficiently strong, the catch  41  could move to the unlock position. By providing the bosses  34 , 35 , no torque is exerted on the catch  41 . As a result, the pivot point  45  of the catch  41  may be located above the projections  21  without fear of the catch  41  moving inadvertently to the unlock position. 
         [0041]    Owing to dimensional and geometric tolerances in the wand  1 , the forces applied to the catch  41  by the projections  21  and the bosses  34 , 35  may not have exactly the same line of action. Accordingly, when a push or pull force is applied to the wand  1 , a torque may be exerted on the catch  41 . However, any torque will be relatively small. Accordingly, even if the applied force is relatively strong, the resulting torque will be insufficient to move the catch  41  to the unlock position. 
         [0042]    The inner tube  3  has a flat section  20  from which the projections  21  project. The flat section  20  is then wider than the projections  21  such that the flat section  20  extends along either side of each projection  21 . This then has the benefit that the bosses  34 , 35  of the outer tube  3  can be located at approximately the same height as the projections  21  in a relatively compact manner In particular, the outer tube  3  may have an inner diameter that is only slightly larger than the outer diameter of the inner tube  2  so as to permit sliding movement. The flat section  20  on the top of the inner tube  2  then provides the space for the bosses  34 , 35  of the outer tube  3 . 
         [0043]    Whilst the outer tube  3  has both front bosses  34  and rear bosses  35 , significant benefits may be achieved by having only front bosses  34  or only rear bosses  35 . For example, when the wand  1  is used to manoeuvre a cleaner head over a surface, the push force applied to the wand  1  is generally greater than the pull force. The provision of rear bosses  35  would therefore enable a pivot to be employed that is capable of bearing the smaller pull force but would yield if subjected to the larger push force. As a further example, the pivot may be designed to bear both the push force and the pull force. The front bosses  34  may then be provided in order to prevent the catch  41  from moving inadvertently to the unlock position when a relatively strong pull force is applied to the wand  1 . 
         [0044]    The inner tube  3  has a plurality of recesses  22  into which the locking stub  44  of the catch  41  can project. This then has the benefit that the length of the wand  1  can be adjusted according to the height of the user or the intended use. Conceivably, however, the inner tube  3  may comprise a single recess  22  located between a single pair of projections  21 . The locking stub  44  would then project into the recess  22  when the wand  1  is fully extended. Only one of the pair of projections  21  would then pass between both the front bosses  34  and the rear bosses  35  when the inner tube  2  slides relative to the outer tube  3 ; the other of the pair of projections  21  would pass between only the rear bosses  35 .