Patent Publication Number: US-2023145802-A1

Title: An apparatus for transporting a load from a first to a second level, in particular a stairlift

Description:
The invention relates to an apparatus for transporting a load from a first to a second level, in particular a stairlift, comprising:
         a frame which is displaceable along a rail and which is provided with support, guide and drive means arranged to engage the rail,   a load carrier which is rotationally mounted on said frame to be rotated around a horizontal axis, and   means for maintaining the load carrier in a predetermined rotational position relative to the direction of gravity, which position-maintaining means comprise at least one adjusting motor arranged to rotate the load carrier relative to the frame around said horizontal axis,   wherein said apparatus further comprises an emergency rotation blocking arrangement for preventing said rotation between the load carrier and said frame, said rotation blocking arrangement comprising:   a first braking member rigidly connected to one of said frame and said load carrier,   a second braking member rigidly connected to the other one of said frame and said load carrier,   at least one third braking member arranged between said first braking member and said second braking member,   a movable retaining member which holds said third braking member and which is arranged to be moved relative to the second braking member;   wherein said first braking member has a primary braking surface which is strip shaped and extends along at least a section of a circle around said axis,   wherein said second braking member has at least one secondary braking surface which extends at a distance from said primary braking surface at an angle in such a manner that the distance between the two surfaces varies, thereby forming a substantially wedge shaped gap between the primary surface and the secondary surface having a wider part and a narrower part, the wedge shaped gap widening in a tangential direction around said axis,   wherein in a normal operation mode said third braking member is held in a fixed position relative to said second braking member by said retaining member such that it extends in the wider part of said wedge shaped gap where it cannot engage both the primary braking surface and the secondary braking surface at the same time, and   wherein in a braking operation mode said retaining member is arranged to be moved relative to said second braking member such that said third braking member moves to the narrower part of said wedge shaped gap, thereby engaging both the primary braking surface and the secondary braking surface and blocking rotation of the second braking member in said tangential direction relative to the first braking member.       

     Such an apparatus is described in EP 3 326 955 A. The emergency blocking mechanism prevents the carrier from uncontrolled rotational movement should the means for maintaining the carrier in the predetermined rotational position fail, in particular to prevent injuries to person sitting on the carrier. 
     The invention aims at an alternative reliable emergency blocking solution. 
     To that end said movable retaining member is designed such that it forces the third braking member to move to the narrower part of said wedge shaped gap when the retaining member is moved relative to said second braking member in said braking operation mode. 
     Preferably in the normal operation mode the third braking member in said fixed position is being held away from the primary braking surface by a surface of a guide. 
     Preferably said retaining member is at least partially made of a flexible material or has an otherwise flexible structure which allows the at least one third braking member to be moved by engagement of the first secondary braking surface and the second secondary braking surface without the retaining member being driven to move said third braking member. 
     Preferably said second braking member comprises at least two secondary braking surfaces, being at least one first secondary braking surface and at least one second secondary braking surface, said at least one first secondary braking surface forming a first substantially wedge shaped gap widening in a first tangential direction around said axis, and said at least one second secondary braking surface forming a second substantially wedge shaped gap widening in a second tangential direction around said axis, said second tangential direction being the opposite of said first tangential direction, and said at least one third braking member being forced by said retaining member in said braking operation mode to move to a narrower part of one of said first and second substantially wedge shaped gaps, thereby forcing said at least one third braking member to block rotation of the second braking member in either tangential direction relative to the first braking member. 
     Preferably said at least first secondary surface and said at least second secondary braking surface form two separate substantially wedge shaped gaps, and said at least one third braking member are at least two separate third braking members, each extending in a respective substantially wedge shaped gap. 
     Preferably said blocking arrangement comprises a multitude of first and secondary braking surfaces forming substantially wedge shaped gaps and a multitude of third braking members, each extending in a respective substantially wedge shaped gap. 
     Preferably said retaining member is at least partially made of a flexible material or has an otherwise flexible structure which allows the multitude of third braking members to be moved relative to each other by engagement of the first secondary braking surface and the second secondary braking surface. 
     Preferably said primary braking surface is a cylindrical surface. 
     Preferably said at least one third braking member has the form of a cylinder, and the axis of said cylinder extends parallel to both the primary and secondary braking surfaces. 
     Preferably said retaining member is held in position in normal operation by the force of an electrically powered electromagnet. 
     Preferably a resilient biasing member is arranged to move said retaining member from said fixed position in normal operation mode to said braking operation mode. 
     Preferably said first braking member is rigidly connected to said load carrier and said second braking member is rigidly connected to said frame. 
    
    
     
       The invention will now be elucidated by means of a preferred embodiment as shown in the figures, wherein: 
         FIG.  1    shows a perspective view of an exemplary embodiment of a stairlift; 
         FIG.  2    shows an exploded perspective view of a displaceable frame and a carrier for a stairlift as shown in  FIG.  1   , with an emergency rotation blocking arrangement mounted there between; 
         FIG.  3    shows an exploded perspective view of the emergency rotation blocking arrangement of  FIG.  2   ; and 
         FIGS.  4 ,  5  and  6    show a front view of the emergency rotation blocking arrangement of  FIG.  3    in normal operation mode, resting or non-operational mode, and in braking operation mode respectively. 
     
    
    
       FIG.  1    shows an system  1  for transporting a load from a first to a second level, in the shown embodiment a stairlift system, which comprises a rail  3  which is placed along a staircase  2  and which encloses an angle α with the horizontal H, and an apparatus  4  movable along rail  3  for transporting the load between the different levels. Rail  3 , which in the shown embodiment has a round cross-section, is supported by a number of posts  5  which are arranged distributed along staircase  2  and which are fixed to a protruding part extending along rail  3 . Rail  3  is further provided with a propelling part in the form of a gear rack. Stairlift  4  comprises a frame  9  which is displaceable along rail  3  and on which a load carrier  10  is mounted, here in the form of a chair with a seat  11 , back rest  12 , armrests  13  and a footrest  14 . Chair  10  is connected to frame  9  by a rotatable shaft  15  and fixation means  16 ,  17  (shown in  FIG.  2   ) for rotating around a horizontal axis, and arranged in frame  9  and carrier  10  is a level maintaining mechanism consisting of, among other parts, of an adjusting motor connected to said shaft  15  so that the position of chair  10  can be kept constant at all times irrespective of the inclination of rail  3 . For further details of an embodiment of a system as shown here, reference is made to European patent application publication EP 2 216 284 A1, which is incorporated herein by reference. This description will hereafter focus on the new emergency rotation blocking arrangement between the frame  9  and the load carrier  10 . 
     According to  FIGS.  2  and  3   , an emergency rotation blocking arrangement is mounted between a frame  9  and a load carrier  10 . The rotation blocking arrangement comprises a first braking member  21 , a second braking member  22 , a plurality of third braking members  23 , and a retaining member  24  for holding the third braking members  23  in position. 
     The first braking member  21  comprises a cylindrical outer surface  212  extending around the hollow shaft  15 . The first braking member  21  is rigidly connected to the load carrier  10  by bolts  213  extending through holes  214  in said body  10 . 
     The second braking member  22  comprises a substantially cylindrical body extending around the cylindrical part  212  of the first braking member  21 , such that it can rotate relative thereto. The second braking member  22  is rigidly connected to the frame  9  by bolts  221  extending through holes  222 . A guide ring  224 , which encloses the first braking member  21  in the axial direction, is provided on each side of the second braking member  22 . 
     The second braking member  22  comprises recesses  223  in its inner circumferential wall around the cylindrical outer surface  212  of the first braking member  21 , such that the surface of said recesses face the outer surface  212 . As shown in  FIGS.  4 ,  5  and  6   , the surface of the recesses  223  is shaped such that the surface of each recess  223  and said surface of the cylindrical part  212  form substantially wedge shaped gaps  231 , having a wider part in its upper region and a narrower part in its lower region. The guide ring  224  of the braking member  22  has a substantially circular shape, and comprises recesses which form guides  2243  that are shaped such that can they engage both outer ends of the third braking members  23  and guide the third braking members  23  away from the surface  212  when they are moved by the retaining member  24  to the upper extreme positions, as shown in  FIG.  4    and as explained below. 
     The third braking members  23  have a cylindrical main body  232  and a shaft  233  extending from both ends. The holders  241  of the retaining member  24  have holes  249  in which the shafts  233  of the third braking members  23  extend. The braking members  23  can freely rotate around the shafts  233 . 
     The retaining member  24  comprises two holders  241 , two lateral arms  242 , a link  243  and a shaft  244 . The shaft  244  is mounted on the load carrier  10  in such a manner that it can move in its axial direction, which direction is perpendicular to the horizontal axial direction of the first braking member  21  and the second braking member  22 , and which axial direction is, in the embodiment as shown, the vertical direction. The link  243  is attached to the shaft  244  and extends perpendicular to the shaft and is allowed to rotate around the axis of the shaft  244 . One end of each of the two lateral arms  242  is attached to the outer end of the link  243  in such a manner that they can rotate around a horizontal axis which is parallel to the horizontal axial direction of the first braking member  21  and the second braking member  22 , and such that they can rotate about an axis which is parallel to said axis of the shaft  244 . The other outer ends of the lateral arms  242  are each attached to a respective holder  241 , in such a manner that the holders  241  can rotate with respect to the arms  242  about an axis which is parallel to the horizontal axial direction of the first braking member  21  and the second braking member  22 . 
     The holders  241  are made of a flexible material, such as a flexible plastic material, such that they can easily deform when forces are exerted on different parts of the holder  241 , in particular by the third braking members  23 . 
     Detectors such as micro switches  245  detect the angular mutual orientation between the arms  242  and the holders  241 , whereby an emergency braking action may be detected, such that the stairlift may be put out of operation until maintenance has occurred. 
     The shaft  244 , the holders  241  and the third braking members  23  that they hold are movable between two respective extreme positions. Two or more biased springs  246  may be provided, of which one end pushes against a third braking member  23 , one on the right side and one the left side as seen in the  FIGS.  4 - 6   , and the other end pushes against a stop surface in the recess  223  of the second braking member  22 , thereby pushing said third braking member  23  and thereby the retaining member  24 , that hold all third braking members  23 , towards their first extreme position. Furthermore an electromagnet  248  is provided, which is mounted on the load carrier  10 . When, in the normal operation mode, the electromagnet  248  is powered, it pulls the shaft  244  of the retaining member  24  in its second extreme (upper) position, against the force of spring  246 , thereby moving the holders  241  of the retaining member  24  and the third braking members  23  towards their second extreme position. If the electromagnet is not powered, the shaft  244  is allowed to move, and the spring  246  may push the holders  241  of the retaining member  24  and the third braking members  23  back towards their first extreme position. 
     In the normal operation mode, as shown in  FIG.  4   , when the retaining member  24  is forced to be in the upper position by the electromagnet  248 , and the retaining member  24  carry the shafts  233  of the third braking members  23  such that their main bodies  232  are forced to extend in the wider parts of the wedge shaped gaps  231  and the third braking members are (just) lifted from the surface  212  by the guides  2243 . In that position the first braking member  21  and the second braking member  22 , and thereby the frame  9  and the load carrier  10 , can freely rotate relative to each other. 
     As shown in  FIG.  5   , in a resting or non-operational mode when the stairlift is not moving, the electromagnet is unpowered, and the retaining member  24  with the holders  241  is forced towards the lower position by the spring  246 , whereby the shafts  233  of the third braking members  23  move towards the narrower part of the wedge shaped gaps  231  at both the left and right sides of  FIG.  5   , such that the of the cylindrical surfaces of the main bodies  232  of the third braking members  23  each touch both the surface  212  of the first braking member  21  and the surface  223  of the second braking member  22 . In that position the friction of the main bodies  232  of the third braking members  23 , prevents rotation between the first braking member  21  and the second braking member  22 , and thereby the frame  9  and the load carrier  10 . 
     In the emergency braking operation mode the electromagnet is also unpowered, for instance in reaction to a signal from a sensor that detects tilting of the load carrier, and the retaining member  24  with the holders  241  is first forced towards the lower position by the spring  246 , as in the resting mode of  FIG.  5   , whereby the shafts  233  of the third braking members  23  move to the narrower part of the wedge shaped gaps  231  at both the left and right sides. However, due to (undesired) rotation of the load carrier  10  and the first braking member  21  attached to it, the third braking members  23  at either the left or the right side (depending on the direction of rotation of the first braking member  21 ) will move further into the narrow side of the gap, which may cause deformation of the materials of for instance the second braking member (as shown in  FIG.  6   ). 
     Said movement of the third braking members will cause their holder  241  to move and thereby also move the other holder  241  of the retaining member  24  with the other third braking members  23  as shown in  FIG.  6   . In that position the friction of the main bodies  232  of the third braking members  23 , and the possible deformation of materials, prevent rotation between the first braking member  21  and the second braking member  22 , and thereby the frame  9  and the load carrier  10 . Thereby the undesired rotation of the load carrier  10  is stopped. 
     The flexibility of the holders  241  allow that in the braking operation mode all the third braking members  23  in the respective holder can and will be engaged by the surface  212  of the first braking member  21  and the respective surfaces  223  of the second braking member  22 , as they are not necessarily held in a mutually fixed position as would be the case with a stiff retaining member. 
     The invention has thus been described by means of a preferred embodiment. It is to be understood, however, that this disclosure is merely illustrative. Various details of the structure and function were presented, but changes made therein, to the full extent extended by the general meaning of the terms in which the appended claims are expressed, are understood to be within the principle of the present invention. The description and drawings shall be used to interpret the claims. The claims should not be interpreted as meaning that the extent of the protection sought is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving any ambiguity found in the claims. For the purpose of determining the extent of protection sought by the claims, due account shall be taken of any element which is equivalent to an element specified therein.