Patent Publication Number: US-2022226176-A1

Title: A combined lift and tilt system and a wheel chair with a built-in seat hoist comprising such a system

Description:
The present invention relates to a combined lift and tilt system, for instance to be mounted in an electric wheel chair for adjustment of the height and/or the inclination of the seat thereof. 
     BACKGROUND OF THE INVENTION 
     The use of lift systems and tilt systems in tables, chairs and beds, etc. is well-known. The majority of such systems operate according to the so-called “scissor principle”. In such systems, a lower frame and an upper frame are connected by two lever arms pivotally connected in a configuration similar to the one of the two arms in a pair of scissors. Most often, there are two pairs of such “scissored” lever arms arranged in two opposite sides of the system, respectively, being driven by a common actuator such as, for instance, a hydraulic or electric linear actuator. 
     Although many good solutions for lift systems and tilt systems are provided using this “scissor principle”, the flexibility of such systems is limited because the function performed, i.e. lifting or tilting, is determined by the mechanical construction of the system. Thus, a given system is designed and constructed to perform either a lifting function or a tilting function (to one side from a horizontal position), and if both a lifting function and a tilting function are required, both a lift system and a tilt system are needed or some kind of mechanical reconfiguration of the system must be performed when switching between the lifting function and the tilting function. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It is an object of the present invention to provide a combined lift and tilt system, which overcomes the above-mentioned disadvantages of lift systems and tilt systems known in the art. 
     The present invention relates to a combined lift and tilt system, which mechanism comprises a lower frame and an upper frame, which are connected by at least one pair of lever arms rotatably connected to each other in a pivotal point, wherein, at least in a contracted configuration of the mechanism, the lower frame and the upper frame are substantially parallel to each other, wherein a first lever arm is rotatably connected at its lowermost end to the lower frame in a fulcrum and the second lever arm is rotatably connected at its uppermost end to the upper frame in a fulcrum and in sliding engagement with the lower frame at its lowermost end in such a way that, when the lowermost end of the second lever arm is moved towards the lowermost end of the first lever arm, the end of the upper frame, to which the uppermost end of the second lever arm is connected, is forced away from the lower frame, wherein a first linear power source, such as a linear actuator, is rotatably connected at its lowermost end to the lower frame in a fulcrum and directly or indirectly connected at its uppermost end to the first lever arm in such a way that an extension of the length of the first linear power source causes the lowermost end of the second lever arm to be pulled towards the lowermost end of the first lever arm, and wherein a second linear power source, such as a linear actuator, is rotatably connected at its uppermost end to the upper frame in a fulcrum and directly or indirectly connected at its lowermost end to the second lever arm in such a way that an extension of the length of the second linear power source causes the end of the upper frame, to which the second power force is connected, to be forced away from the second lever arm. 
     Such a combined lift and tilt system enables for simultaneously performing both lifting and tilting functions (to both sides from a horizontal position) with a single system. 
     In an embodiment of the invention, the sliding engagement between the second lever arm and the lower frame is obtained by means of a roller or a slider suspended in a suspension point at the lowermost end of the second lever arm. 
     In an embodiment of the invention, the first linear power source is connected to the first lever arm in a way that is symmetric to the way, in which the second linear power source is connected to the second lever arm. 
     If the system is “mirrored” like this, it means that a parallel lift of the upper frame from the lower frame can be obtained by controlling the two linear power sources simultaneously and identically. 
     In an embodiment of the invention, the combined lift and tilt system further comprises a control system arranged to be able to control the motions of the first and second linear power source individually and/or simultaneously. 
     In an embodiment of the invention, the combined lift and tilt system is dimensioned to be able to lift a load of at least 180 kg, preferably at least 250 kg. 
     In an embodiment of the invention, the combined lift and tilt system is dimensioned to be able to lift a load over a range of at least 250 mm, preferably at least 300 mm. 
     In an embodiment of the invention, the combined lift and tilt system is dimensioned so that the height thereof in a fully collapsed configuration is less than 125 mm, preferably less than 90 mm. 
     In an embodiment of the invention, the combined lift and tilt system is configured to be able to tilt the upper frame in an angle of at least 40°, preferably at least 60°, compared to the lower frame to one side or the other. 
     A lift and tilt system with such characteristics is very suitable for being used in applications with limited space and demands for a high lifting capacity and flexible tilt functions like, for instance, as a built-in seat hoist in a wheel chair. 
     In another aspect of the invention, it relates to a wheel chair with a built-in seat hoist comprising a combined lift and tilt system according to any of the preceding claims. 
    
    
     
       DRAWINGS 
       In the following, a few exemplary embodiments of the invention are described in more detail with reference to the drawings, of which 
         FIG. 1 a    is a principle sketch or a lift and tilt system according to a first embodiment of the invention in a fully collapsed configuration, 
         FIG. 1 b    is a principle sketch of the same lift and tilt system in a fully lifted configuration, 
         FIG. 1 c    is a principle sketch of the same lift and tilt system in a fully positively tilted configuration, 
         FIG. 1 d    is a principle sketch of the same lift and tilt system in a fully negatively tilted configuration, 
         FIG. 1 e    is a perspective view of the same lift and tilt system in a fully lifted and slightly positively tilted configuration, 
         FIG. 2 a    is a principle sketch or a lift and tilt system according to a second embodiment of the invention in a fully collapsed configuration, 
         FIG. 2 b    is a principle sketch of the same lift and tilt system in a partly lifted configuration, 
         FIG. 2 c    is a principle sketch of the same lift and tilt system in a fully lifted configuration, 
         FIG. 2 d    is a principle sketch of the same lift and tilt system in a fully positively tilted configuration, 
         FIG. 2 e    is a principle sketch of the same lift and tilt system in a fully negatively tilted configuration, 
         FIG. 3 a    is a principle sketch or a lift and tilt system according to a third embodiment of the invention in a fully collapsed configuration, 
         FIG. 3 b    is a principle sketch of the same lift and tilt system in a partly lifted configuration, 
         FIG. 3 c    is a principle sketch of the same lift and tilt system in a fully lifted configuration, 
         FIG. 3 d    is a principle sketch of the same lift and tilt system in a fully positively tilted configuration and 
         FIG. 3 e    is a principle sketch of the same lift and tilt system in a fully negatively tilted configuration, 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 a -1 d    are principle sketches of a lift and tilt system  1  according to a first embodiment of the invention in a fully collapsed, in a fully lifted, in a fully positively tilted and in a fully negatively tilted configuration, respectively.  FIG. 1 e    is a perspective view of the same lift and tilt system  1  in a fully lifted and slightly positively tilted configuration. 
     A first lever arm  4  and a second lever arm  5 , which are rotatably connected to each other in a pivotal point  6 . In practice, there is such a pair of lever arms  4 ,  5  in both sides of the lift and tilt system  1 . For the sake of explanation, however, the following section explains the function of one such pair of lever arms  4 ,  5 . 
     The first lever arm  4  is rotatably connected at its lowermost end to a lower frame  2  in a fulcrum  7  and at its uppermost end to the pivotal point  16 . The second lever arm  5  is rotatably connected at its uppermost end to an upper frame  3  near a first end thereof in a fulcrum  8  and in sliding engagement with the lower frame  2  at its lowermost end by means of a roller  13 , which is suspended in a suspension point  14  on the second lever arm  5 . 
     A first torque arm  15  is rotatably connected to the lower frame  2  in a fulcrum  17  and provided with a suspension point  22 , in which a roller or slider  21  is suspended. A first linear power source  9 , such as a linear actuator, is rotatably connected at its lowermost end to the lower frame  2  in a fulcrum  10  and rotatably connected at its uppermost end to the first torque arm  15  in a suspension point  16 . 
     The first linear power source  9  and the first torque arm  15  are configured in such a way that, when the length of the first linear power source  9  is extended, the first torque arm  15  rotates around the fulcrum  17  and the roller or slider  21  on the first torque arm  15  moves in a downward direction along the first lever arm  4 . Thereby, the pivotal point  6  and the first end of the upper frame  3 , to which the second lever arm  5  is connected, is forced away from the lower frame  2 . 
     A similar construction constitutes the remaining part of lift and tilt system  1 : 
     A second torque arm  18  is rotatably connected to the upper frame  3  in a fulcrum  20  and provided with a suspension point  24 , in which a roller or slider  23  is suspended. A second linear power source  11 , such as a linear actuator, is rotatably connected at its uppermost end to the upper frame  3  in a fulcrum  12  near a second end thereof opposite the first end, at which the second lever arm  5  is connected. At its lowermost end, the second linear power source  11  is rotatably connected to the second torque arm  18  in a suspension point  19 . 
     The second linear power source  11  and the second torque arm  18  are configured in such a way that, when the length of the second linear power source  11  is extended, the second torque arm  18  rotates around the fulcrum  20  and the roller or slider  23  on the second torque arm  18  moves in an upward direction along the second lever arm  5 . Thereby, the second end of the upper frame  3  is forced away from the lower frame  2 . 
     When both of the linear power sources  9 ,  11  are in their most contracted states, the lower frame  2  and the upper frame  3  are parallel to each other, and the lift and tilt system  1  is fully collapsed as illustrated in  FIG. 1   a.    
     If the lower frame  2  is placed on a more or less horizontal surface, this means that a lift of the upper frame  3  can be obtained by extending the respective lengths of the two linear power sourced  9 ,  11  in such a way that the first and second ends of the upper frame  3  are kept at the same distance from the lower frame  2  at all times. This is most easily obtained if the two halves of the system are identical, in which case a parallel lift can be obtained by controlling the two linear power sources  9 ,  11  simultaneously and identically. 
     A positive tilt as the one illustrated in  FIG. 1 c    can be obtained by activating only the first linear power source  9 , whereas a negative tilt as the one illustrated in  FIG. 1 d    can be obtained by activating only the second linear power source  11 . 
       FIGS. 2 a -2 e    are principle sketches of a lift and tilt system  1  according to a second embodiment of the invention in a fully collapsed, in a partly lifted, in a fully lifted, in a fully positively tilted and in a fully negatively tilted configuration, respectively. The function of this second embodiment is the same as the function of the first embodiment and the construction of the second embodiment is rather similar to that of the first embodiment. 
     Basically, the differences between the first and second embodiments are the following:
         the rollers or sliders  21 ,  23  on the first torque arm  15  and the second torque arm  18 , respectively, have been removed   a first lifting arm  25  is arranged between the suspension point  22  on the first torque arm  15  and a suspension point  26  on the first lever arm  4     a second lifting arm  27  is arranged between the suspension point  24  on the second torque arm  18  and a suspension point  28  on the second lever arm  5         

       FIGS. 3 a -3 e    are principle sketches of a lift and tilt system  1  according to a third embodiment of the invention in a fully collapsed, in a partly lifted, in a fully lifted, in a fully positively tilted and in a fully negatively tilted configuration, respectively. The function of this second embodiment is the same as the function of the first and second embodiments and the construction of the third embodiment is rather similar to that of the second embodiment. 
     Basically, the differences between the second and third embodiments are the following:
         the first torque arm  15  has been replaced by a first control arm  29  extending between the suspension point  16  on the first linear power source  9  and the fulcrum  17     the second torque arm  18  has been replaced by a second control arm  30  extending between the suspension point  19  on the second linear power source  11  and the fulcrum  20     the first lifting arm  25  is arranged between the suspension point  16  on the first linear power source  9  and the suspension point  26  on the first lever arm  4     the second lifting arm  27  is arranged between the suspension point  19  on the second linear power source  11  and the suspension point  28  on the second lever arm  4         

     As mentioned, a mirrored/symmetric configuration of the lift and tilt system  1  will typically be advantageous, primarily for simplifying the control of the two linear power sources  9 ,  11  during lifting operations, in which the two ends of the upper frame  3  must be lifted simultaneously. In special cases, however, it might be necessary to sacrifice the symmetry if specific functions are required. This could, for instance, be the case if a “stand up function” is a required in a wheel chair, which requires a positive tilt of the seat of up to as much as around 80°. 
     LIST OF REFERENCE NUMBERS 
     
         
         
           
               1 . Lift and tilt system 
               2 . Lower frame 
               3 . Upper frame 
               4 . First lever arm 
               5 . Second lever arm 
               6 . Pivotal point for first lever arm and second lever arm 
               7 . Fulcrum for first lever arm on lower frame 
               8 . Fulcrum for second lever arm on upper frame 
               9 . First linear power source 
               10 . Fulcrum for first linear power source on lower frame 
               11 . Second linear power source 
               12 . Fulcrum for second linear power source on upper frame 
               13 . Roller or slider on second lever arm 
               14 . Suspension point for roller or slider on second lever arm 
               15 . First torque arm 
               16 . Suspension point on first linear power source 
               17 . Fulcrum on lower frame 
               18 . Second torque arm 
               19 . Suspension point on second linear power source 
               20 . Fulcrum on upper frame 
               21 . Roller or slider on first torque arm 
               22 . Suspension point on first torque arm 
               23 . Roller or slider on second torque arm 
               24 . Suspension point on second torque arm 
               25 . First lifting arm 
               26 . Suspension point for first lifting arm on first lever arm 
               27 . Second lifting arm 
               28 . Suspension point for second lifting arm on second lever arm 
               29 . First control arm 
               30 . Second control arm