Patent Publication Number: US-2013240294-A1

Title: Vertically Adjustable Automatic Step Stool

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/021,998 filed on Feb. 7, 2011. This application claims the benefit and priority of U.S. Provisional Application No. 61/301,654, filed on Feb. 5, 2010. The entire disclosure of each of the above applications is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to step stools, and more particularly, to automatic step stools that are vertically adjustable. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Traditional step stools include collapsible steps that allow a user to elevate the user&#39;s body from the floor by climbing the steps. However, the user may be unable to climb steps due to a physical disability. Step stools or platforms have been developed that adjust automatically using a scissors-type linkage. However, these step stools are not suitable for home or hospital use and/or cause significant wear on the actuators used to adjust these step stools. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A step stool includes an inner frame, an outer frame, an actuator, and a coupler. The inner frame includes two inner pillars, and the outer frame includes two outer pillars attached to a platform near opposite ends of the platform and configured to receive the two inner pillars. The actuator is coupled to one of the two inner pillars and one of the two outer pillars, and is operable to raise the outer frame relative to the inner frame. The coupler couples the two outer pillars to each other to evenly lift the opposite ends of the platform when the actuator raises the outer frame. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a isometric view of a step stool according to the principles of the present disclosure, with the step stool in a lowered position; 
         FIG. 2A  is a first isometric view of the step stool of  FIG. 1 , with the step stool in a raised position; 
         FIG. 2B  is a close-up view of a portion of  FIG. 2A  within the line  2 B; 
         FIG. 3  is a second isometric view of the step stool of  FIG. 1 , with the step stool in the raised position; 
         FIG. 4  is a top view of the step stool of  FIG. 1 ; 
         FIG. 5  is a front view of the step stool of  FIG. 1 ; 
         FIG. 6  is a side view of the step stool of  FIG. 1 ; 
         FIG. 7  is a section view of the step stool of  FIG. 1  taken along the line  7 - 7  shown in  FIG. 5 ; 
         FIG. 8A  is a section view of the step stool of  FIG. 1  taken along the line  8 - 8  shown in  FIG. 5 ; 
         FIG. 8B  is a close-up view of a portion of  FIG. 8A  within the line  8 B; 
         FIG. 9  is a partial section view of the step stool of  FIG. 1  taken along the line  9 - 9  shown in  FIG. 5 ; 
         FIG. 10A  is a section view of the step stool of  FIG. 1  taken along the line of  FIG. 10-10  shown in  FIG. 4 ; 
         FIG. 10B  is a close up view of a portion of  FIG. 10A  within the line  10 B; 
         FIG. 11  is a section view of the step stool of  FIG. 1  taken along the line  11 - 11  shown in  FIG. 5 ; 
         FIG. 12  is an isometric view of a first alternate embodiment of a step stool according to the principles of the present disclosure; 
         FIG. 13  is an isometric view of a second alternate embodiment of a step stool according to the principles of the present disclosure; and 
         FIG. 14  is a section view of the step stool of  FIG. 13  taken along the line  14 - 14  shown in  FIG. 13 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. 
     Spatially relative terms, such as “left,” right,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     As used herein, the term module may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC); an electronic circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; other suitable components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip. The term module may include memory (shared, dedicated, or group) that stores code executed by the processor. 
     The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, and/or objects. The term shared, as used above, means that some or all code from multiple modules may be executed using a single (shared) processor. In addition, some or all code from multiple modules may be stored by a single (shared) memory. The term group, as used above, means that some or all code from a single module may be executed using a group of processors. In addition, some or all code from a single module may be stored using a group of memories. 
     Referring now to  FIGS. 1 through 6 , a step stool  10  according to the principles of the present disclosure will now be described. The step stool  10  can be adjusted automatically in the vertical direction. Thus, the step stool  10  is suitable for home use, hospital use, industrial use, and other types of uses. 
     The step stool  10  includes a lower or inner frame  12  and an upper or outer frame  14 . The outer frame  14  is configured to receive the inner frame  12  so that the outer frame  14  can be placed over the inner frame  12 . A sliding mechanism  16  guides the outer frame  14  relative to the inner frame  12 . The sliding mechanism  16  allows the outer frame  14  to slide relative to the inner frame  12  with relatively low friction resistance. The slide mechanism  16  can be positioned on the forward and rearward faces of the pillars  26 ,  28 , as shown, or at another suitable location. 
     An actuator  18  is coupled to the inner frame  12  and the outer frame  14 . The actuator  18  is operable to raise and lower the outer frame  14  relative to the inner frame  12 . The actuator  18  depicted includes a solenoid motor that receives power via a power cord  19 . Alternatively, the actuator  18  can receive power from batteries, which can be rechargeable, and the power cord  19  can be omitted. Although the actuator  18  is depicted as including a solenoid motor, the actuator  18  can be electric, pneumatic, and/or hydraulic. 
     A coupler  20 , such as a chain and sprocket mechanism, couples opposite lateral ends of the outer frame  14  to ensure that opposite lateral ends of the outer frame  14  are raised and lowered evenly. The actuator  18  is fixed to the left side of the inner frame  12  and the left side of the outer frame  14 . Thus, as the actuator  18  extends, the actuator  18  exerts an upward force on the left side of the outer frame  14  to move the left side of the outer frame  14  is moved upward. As the left side of the outer frame  14  is moved upward, an upward force is exerted on the left side of the coupler  20 . The coupler  20  transmits this upward force to the right side of the outer frame  14  such that equal upward forces are exerted on opposite lateral ends of the outer frame  14 . 
     A control module  22  housed in a control box  23  communicates with a user interface  24  via a wire  25 . The control box  23  includes an upper box  23   a  and a lower box  23   b . The control module  22  controls the actuator  18  based on input received from a user via the user interface  24 . Although the control box  23  is shown mounted to the left side of the inner frame, the control box  23  can be mounted to another suitable location such as to the center of the inner frame  12  underneath the outer frame  14 . Similarly, although the user interface  24  is shown as a remote control connected via the wire  25 , the user interface  24  can be integrated into the outer frame  14 , or into a handle fixed to the outer frame  14 , and the wire  25  can be omitted. 
     The user interface  24  includes one or more buttons and/or a touch screen that allow a user to command the step stool to raise and lower. The control module  22  can include relays, switches, and/or a power supply. The relays can open and close based on whether the user commands the step stool to raise or lower. The switches can be limit switches that stop the actuator  18  from extending or retracting when a travel limit has been met. The travel limit can be preset by the manufacturer of the step stool and/or adjusted by the user. For example only, the travel limit can be preset to approximately 25 inches. The power supply can convert power provided by the power cord  19  into power required by the actuator  18 . 
     The inner frame  12  includes a right column or pillar  26 , a left column or pillar  28 , a cross-beam  30 , wheel brackets  32 , and brake brackets  34 . The cross-beam  30  connects the right pillar  26  to the left pillar  28 . The inner frame  12  can be made of metal, such as steel or aluminum, or plastic, such as polyurethane. Wheels  36 , such as castor wheels, are attached to the wheel brackets  32 . The wheels  36  enable a user to roll the step stool  10  to a desired position. 
     The step stool  10  can include one or more motors that drive the wheels  36 , and the user may control motion of the wheels  36  via the user interface  24 . In one example, a motor can be coupled to each of the wheels  36  to independently drive the wheels  36 . In another example, a single motor, such as the motor included in the actuator  18 , can be used in conjunction with a spider gear system to independently drive the wheels  36 . Independently driving the wheels  36  allows the user to automatically move the step stool  10  forward, rearward, and in a turning direction. 
     Object sensors  38 , such as infrared sensors, can be mounted to the wheel brackets  32  or to another suitable location. The object sensors  38  detects objects underneath the outer frame  14  and inform the control module  22  when objects are detected. The control module  22  prevents the actuator  18  from lowering the outer frame  14  when objects are detected. 
     Stabilizer feet or brakes  40  are mounted to the under side of the brake brackets  34 . The brakes  40  can be manually adjusted by the user to engage the floor and thereby prevent the step stool  10  from rolling on the wheels  36 . Although the brakes  40  are depicted as manually adjustable, the brakes  40  can be automatically adjusted via the control module  22 , the user interface  24 , and an actuator that actuates the brakes  40 . In addition, although the brakes  40  are depicted as engaging the floor, the brakes  40  can engage the wheels  36  to prevent wheels  36  from rolling and thereby prevent the step stool  10  from rolling. 
     The outer frame  14  includes a platform  42  having a forward ramped end  43 . The outer frame  14  also includes a left column or pillar  44  and a right column or pillar  46  positioned near opposite lateral ends of the platform  42 . The outer frame  14  further includes a right handle  48  and a left handle  50  mounted on top of the right pillar  44  and the left pillar  46 , respectively. The platform  42  can be corrugated to prevent a user from slipping. The ramped end  43  provides a gradual transition from the floor to the top surface of the platform  42  to assist the user in stepping or rolling a wheelchair onto the platform  42 . The platform  42 , the pillars  44 ,  46 , and the handles  48 ,  50  can be made of metal, such as steel or aluminum, or plastic, such as polyurethane. 
     The pillars  44 ,  46  and the handles  48 ,  50  serve as safety rails or guiderails that prevent the user from falling down and/or from falling off of the platform  42 . As shown, the handles  48 ,  50  are generally tubular and form oval rings that the user can grab onto. However, the handles  48 ,  50  can have various shapes, sizes, and textures that enable the user to grip the handles  48 ,  50 . 
     With specific reference to  FIG. 2B , the sliding mechanism  16  includes an outer bracket  52  fixed to the inner frame  12 , an inner bracket  54  fixed to the outer frame  14 . The sliding mechanism  15  also includes fasteners  56  fixing the outer bracket  52  and the inner bracket  54  to the inner frame  12  and the outer frame  14 , and bearings  58 , such as bearing balls, positioned between the outer bracket  52  and the inner bracket  54 . The outer bracket  52  can nestingly receive the inner bracket  54  and the bearings  58  can be captured between the outer bracket  52  and the inner bracket  54 . The bearings  58  reduce friction between the inner frame  12  and the outer frame  14  as the actuator  18  moves the outer frame  14  relative to the inner frame  12 . In turn, wear on the actuator  18  is minimized, thereby extending the life of the actuator  18 . 
     Referring now to  FIG. 7 , the coupler  20  includes one or more chains  60 , lower sprockets  62 , and upper sprockets  64 . The chains  60  are routed around the perimeter of the sprockets  62 ,  64  and mesh with teeth of the sprockets  62 ,  64 . As discussed in more detail below, the sprockets  62 ,  64  change the direction of an upward force exerted on one end of the chains  60  so that other end the chains  60  exert an upward force on the outer frame  14 . 
     The outer frame  14  includes lower brackets  66  to which the platform  42  is mounted. The platform  42  can be attached to the brackets  66  via fasteners  68 , or by an alternative attachment method such as welding. The outer frame  14  also includes brackets  70  to which a cover plate  72  is attached. The cover plate  72  can be attached to the brackets  70  via fasteners  74 , or by an alternative attachment method such as welding. Although only the right side of the step stool  10  is shown, the platform  42  and the handle  50  can be attached to the outer frame  14  in a similar manner on the left side of the step stool  10 . 
     Referring now to  FIG. 8A , the actuator  18  includes a solenoid motor  76 , a gear box  78 , a cylinder  80 , and a piston  82 . The motor  76  rotates gears in the gear box  78  to extend and retract the piston  82  within the cylinder  80 . The inner frame  12  includes a bracket  84  to which the bottom of the actuator  18  is mounted. A fastener  86 , such as a pin, is used to fasten the bottom of the actuator  18  to the bracket  84  of the inner frame  12 . The outer frame  14  includes a bracket  86  to which the top of the actuator  18  is mounted. A fastener  88 , such as a pin, is used to fasten the top of the actuator  18  to the bracket  86  of the outer frame  14 . 
     Referring now to  FIG. 8B , the wheels  36  can be mounted to the wheel brackets  32  using swivel brackets  88 . Fasteners  90  can be used to attach the swivel brackets  88  to the wheel brackets  32 . Alternatively, the swivel brackets  88  can be welded to the wheel brackets  32 . The swivel brackets  88  allow the wheels  36  to rotate about a vertical axis, which enables a user to rotate the step stool  10  about a vertical axis. In turn, the maneuverability of the step stool  10  is improved. The swivel brackets  88  offset the axes of the wheels  36  from the vertical axis about which the wheels rotate. Thus, the wheels  36  are mounted at a caster angle, which stabilizes movement of the wheels  36  and reduces loading on the swivel brackets  88 . The swivel brackets are mounted to the wheel brackets  32  using fasteners  90 . 
     Referring now to  FIG. 9 , fasteners  92 , such as pins or screws, can be used to attach the wheels  36  to the swivel brackets  88 . The wheels  36  rotate about the fasteners  92 . In this regard, the fasteners  92  act as axels about which the wheels  36  rotate. 
     Near the center of the step stool  10 , a retaining clip  94  can be used to retain the pin  86  within the bracket  84  of the inner frame  12 . As discussed above, the bottom of the actuator  18  can be attached to the inner frame  12  using the bracket  84  and the pin  86 . The retaining clip  94  can be easily removed from the pin  86  when repairing or replacing the actuator  18 . 
     Referring now to  FIG. 10A  with continued reference to  FIG. 9 , the chains  60  of the coupler  20  include a first end  96  attached to the outer frame  14  via a chain bar  98 . The chain bar  98  can be attached to the outer frame  14  using fasteners  100 . Alternatively, the chain bar  98  can be welded to the outer frame  14 . The chain bar  98  traps or clamps the first end  96  of the chains  60  to fix the first end  96  of the chains  60  to the outer frame  14 . 
     The chains  60  also include a second end  102  fixed to the outer frame  14  using a chain bar  104 . The chain bar  104  clamps the second end  102  of the chains  60  to fix the second end  102  of the chains  60  to the outer frame  14 . The chain bar  104  can be fastened or welded to the outer frame  14 . 
     The chains  60  include chain sections  60   a ,  60   b ,  60   c , and  60   d . The lower sprockets  62  include a left sprocket  62   a  and a right sprocket  62   b . The chain section  60   a  extends between the second end  102  of the chains  60  and the upper sprocket  64 . The chain section  60   b  extends between the upper sprockets  64  and the lower sprocket  62   b . The chain section  60   c  extends between the lower sprocket  62   b  and the lower sprocket  62   a . The chain section  60   d  extends between the lower sprocket  62   a  and the first end  96  of the chains  60 . 
     The coupler  20  can further include one or more roller guides  106  that guide the chain  60  as the chain  60  is pulled around the sprockets  62 ,  64 . As discussed in more detail below, the roller guides  106  can be included as part of tensioners  108  that can be adjusted by a user to adjust the tension of the chain  60 . The tensioners  108  can be adjusted using a fastener  110 , such as a screw, that alters the height of the roller guides  106  relative to a pivot. 
     Referring now to  FIG. 10B , the brakes  40  can include a pedal or lever  112 , a link  114 , and a fastener  116 , such as a pin or a rivet, fastening the lever  112  to the link  114 . The inner frame  12  can include a bracket  118  to which the link  114  is fastened. The link  114  can be fastened to the bracket  118  of the inner frame  12  using a fastener  120 , such as a pin or a rivet. 
     The brakes  40  can further include a lockout rod  122  that is fastened to the lever  112  via a fastener  124 , such as a pin or a rivet. A bracket  126  includes a slot that guides the fastener  124  in the vertical direction, a leg beneath the slot attached to a pad  128 , and a cup extending from the leg that capture a spring  130 . The lockout rod  122  can be vertically adjusted via the lever  112  to a released position, as shown, in which the pad  128  does not engage the floor, and to a locked position, in which the pad  128  engages the ground. Friction maintains the lockout rod  122  in the locked position. The spring  130  acts against the bracket  126  and the pad  128  to bias the pad  128  toward the floor. 
     To set the brakes  40 , the user can step on or depress the outside end of the lever  112 , causing the lever  112  to rotate about the fastener  124  in a counterclockwise direction. In this regard, the fastener  124  acts as a pivot. As the lever  112  rotates counterclockwise, the fastener  124  is also moved downward in the slot of the bracket  126  due to the downward force of the lever  112 . The counter clockwise motion of the lever  112  causes the link  114  to rotate in a clockwise direction. When the lever  112  and the link  114  are aligned or rotated just beyond alignment, the lockout rod  122  is friction fit in the locked position. This friction fit prevents the lever  112  and the link  114  from returning to the released position shown in  FIG. 10B . In the locked position, the pad  128  engages the floor and the spring  130  biases the pad  128  against the floor. 
     Referring now to  FIG. 11 , the brakes  40  can further include a release lever  132 . A user can step on or depress the release lever  132  to disengage the lockout rod  122 . When the lockout rod  122  is disengaged, the lever  112  and the link  114  are allowed to return to the released position shown in  FIG. 10B . In the released position, the pad  128  does not contact the floor, and therefore the step stool  10  can be rolled freely across the floor. 
     The tensioners  108  include the roller guides  106 , the adjustment bolts  110 , levers  134 , and pivots  136 . The chain section  60   c  can be routed above or below the roller guides  106 , and the fasteners  110  can be loosened or tightened to adjust the height of the roller guides  106  relative to the pivots  136 . Thus, by loosening or tightening the fastener  110 , the user can adjust the tension in the chain  60 . 
     Referring again to  FIGS. 1 through 11 , operation of the step stool  10  will now be described in detail. A user can enter the step stool  10  when the step stool  10  is in a lower position, as shown in  FIG. 1 . The user can enter the step stool  10  by stepping, or if the user is in a wheel chair or a wheel stand, by rolling over the ramped end  43  of the platform  42 . When the user is positioned on top of the platform  42 , the user can manipulate the user interface  24  to command the step stool  10  to rise. The user interface  24  communicates the user&#39;s command to the control module  22 , which in turn controls the actuator  18  to raise the step stool  10  to a raised position, as shown in  FIGS. 2A and 3 . 
     With specific reference to  FIG. 8A , when the control module  22  controls the actuator  18  to raise the step stool  10 , the motor  76  drives gears in the gear box  78  to move the piston  82  upward within the cylinder  80 . As the piston  82  moves upward, the piston  82  moves the outer frame  14  upward relative to the inner frame  12 . Upward movement of the piston  82  within the cylinder  80  can be referred to as extension of the actuator  18 . Downward movement of the piston  82  within the cylinder  80  can be referred to as retraction of the actuator  18 . 
     With specific reference to  FIG. 10A , as the actuator  18  moves the outer frame  14  upward, the outer frame  14  pulls the first end  96  of the chain  60  in the upward direction. The upward force on the first end  96  of the chain  60  creates tension in the chain  60  that pulls the second end  102  up the chain  60  in the upward direction. In this manner, the coupler  20  transmits the upward force exerted on the left side of the outer frame  14  to the right side of the outer frame  14 , which causes the lateral opposite sides of the outer frame  14  to rise evenly. 
     Referring now to  FIG. 12 , a step stool  137  is similar to the step stool  10  such that only differences in the step stools  10 ,  137  will now be described. The step stool  10  can have larger dimensions suitable for industrial use, and the step stool  137  can have smaller dimensions suitable for home use. The step stool  137  includes a right handle  138 , a left handle  140 , and a user interface  142 . The handles  138 ,  140  are generally tubular and have a straight pole shape that can be gripped by a user. The user interface  142  is integrated into the top of the left pillar  46  and includes a button or a touch screen. The platform  42  has a generally square shape and the control module  22  is mounted underneath the platform  42 . The control module  22  can be mounted within a control box that is fixed to the inner frame  12 . Operation of the step stool  137  is similar to that of the step stool  10  with the exception that the user controls the integrated user interface  142  rather than the remote user interface  24 . 
     Referring now to  FIGS. 13 and 14 , a step stool  144  is similar to the step stool  10  such that the only differences in the step stools  10 ,  144  will now be described. While the step stool  10  includes two columns or pillars, the step stool  144  includes only one pillar, the pillar  46 . In addition, the pillar  46  is not positioned near a lateral end of the platform  42 , but rather is positioned near the rearward end of the platform  42  approximately midway between the opposite lateral ends of the platform  42 . The step stool  144  includes the pole handle  140  and the integrated user interface  142 , discussed above with reference to the step stool  137  of  FIG. 12 . 
     The step stool  144  includes a coupler  146  that couples the inner surface of the pillar  46  to the underside surface of the platform  42 . The coupler  146  includes a chain  148  having a first end  150  and a second end  152 . The first end  150  of the chain  148  is attached to the inner surface of the pillar  46  by, for example, a chain bar welded or fastened to the inner surface of the pillar  46  and clamping the first end  150  of the chain  148 . The second end  152  of the chain  148  is attached to the underside surface of the platform  42  by, for example, a chain bar fastened or welded to the underside surface of the platform  42  and clamping the second end  152  of the chain  148 . 
     The coupler  148  also includes a forward upper sprocket  154 , a rearward upper sprocket  156 , a rearward lower sprocket  158 , a forward lower sprocket  160 , and a middle sprocket  162 . The chain  148  includes chain sections  148   a ,  148   b ,  148   c ,  148   d , and  148   e . The chain section  148   a  extends between the first end  150  of the chain  148  and the sprocket  154 . The chain section  148   b  extends between the sprocket  154  and the sprocket  156 . The chain section  148   c  extends between the sprocket  156  and the sprocket  158 . The chain section  148   d  extends between the sprocket  158  and the sprocket  160 . The chain section  148   e  extends between the sprocket  160  and the second end  152 . 
     With continued reference to  FIGS. 13 and 14 , operation of the step stool  144  will now be described in detail. When the user commands the step stool  144  to rise via the user interface  142 , the actuator  18  extends to exert an upward force at the top of the pillar  46 . The pillar  46  transmits this upward force to the first end  150  of the chain  148 , which creates tension in the chain  148 . This tension extends through the chain  148  from the section  148   a , to the section  148   b , to the section  148   c , to the section  148   d , and finally to the section  148   e . As the tension is transmitted through the sections  148   d  and  148   e  of the chain  148 , an upward force is exerted on the sprocket  160 . In this manner, the coupler  148  transfers the upward force exerted by the actuator  18  onto the pillar  46  to an upward force exerted on the forward end of the platform  42 . Thus, the coupler  148  ensures that the longitudinal ends of the platform  42  are evenly raised. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.