Abstract:
An automated pivoting stairway system that raises and lowers through use of a drive actuator to thereby provide access to above or below floor level areas or between an elevated area and the ground floor. The system may utilize modular sections to allow on-site assembly. The stairway may be pivoted at the top of the stairway by way of a pivot drive lever attached on either side of the top step pivot frame assembly so that access on or off the stairway may be directly off the front end of the stairway, or to either side. A separate frame member may extend from the pivot point along the side of the stairway opening to a predetermined distance. This frame member may serve as the anchor point for the base end mount of the actuator. 
     The actuator controls the length of stroke and the amount of torque that is required to operate the stairway up and down.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/195,635, filed 9 Oct. 2008. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to systems and methods for stairway configurations, and more particularly to pivoting stairway systems and methods. 
         [0003]    For many years, there has been an interest in systems and methods which offer convenient access to storage space on adjacent floors of a building. The search to create this access has resulted in the creation of numerous approaches and types of ladders or stairway systems. 
         [0004]    Stowing stairways and ladders that may be retracted, pivoted or folded into ceiling openings are known from several U.S. patents, including U.S. Pat. Nos. 4,541,508, 3,789,955, 6,981,572, and 6,802,392. The access devices described in these patents are generally either pull down retractable or foldable ladders that may be stored in the ceiling of a building, or cable driven and articulating stair units that retract up into the area being accessed. 
         [0005]    The foldable or retractable ladder/stairways are typically spring loaded or counterbalanced and may be difficult for users to fold/unfold and pull up/down from the ceiling level before or after use. Further, the steep angle and step design of these devices make them difficult and dangerous to climb, particularly while the user carries bulky objects, such as storage bins. Additionally, known units having an extended counterbalance do not allow the user straight access on and off the unit at the upper level. Rather, the user must sidestep on or off the stairway at the upper level. This may also result in an unsafe operation. 
         [0006]    The known cable-driven units also offer several disadvantages to the user. For example, cable-driven units typically utilize multiple pulleys and cable termination points, all of which are subject to wear and/or to service requirements, and even eventual failure which may result in the falling of the unit. 
         [0007]    Further, due to these noted design limitations, known foldable or retractable ladder/stairways may not meet building industry standards of a safe staircase design. 
         [0008]    Therefore, there is a need for an improved foldable or retractable ladder/stairway system and method of pivoting such a system. Contemplated improvements may include improvement in design and installation, to thereby provide features not found in current stowable stairway systems. 
       SUMMARY OF THE INVENTION 
       [0009]    The present system and method is believed to ameliorate the above mentioned problems through use of an actuator for stairway movement. The present invention may be described as a pivotable stairway that uses an actuator, such as a screw-drive linear actuator, for raising and lowering the stairway. The present arrangement results in secure, stable and safe to use systems and methods, with the present invention herein described generally as an actuator driven pivoting stairway [ADPS]. 
         [0010]    The main object of the actuator driven pivoting stairway is to provide a stable, safe and efficient access from one floor level to another, whether the floor is above or below, or the installation is inside or outside the main building. 
         [0011]    The unique design of the ADPS provides the user with facile, straight off and straight on access at the entrance or exit of the stairway. The straight off and on access may be provided at either or both the top and bottom of the stairway, and eliminates the need to sidestep on or off the stairway, as in known arrangements. This feature may be accomplished through the use of an actuator which may be mounted to the stairway on one or both sides of the stairway unit. 
         [0012]    A preferred embodiment of the present invention uses a screw-drive linear actuator to create the motion and force to raise and lower the pivoting stairway. With the actuator drive creating the pivoting movement for the stairway, there is no need for other mechanical devices, such as cables, pulleys, counterbalance weights or springs, although they may be used to supplement the actuator. 
         [0013]    A preferred method of installation of the invention includes mounting an actuator to a pivot bracket on one side of the stairway, providing a drive lever, and mounting the drive lever to the upper floor. It is to be understood that other methods of installation are possible, depending on the configuration of the installation site. 
         [0014]    It is also envisioned that the invention may include upper and lower load limit safety sensors that control the screw drive actuator, to maintain operational control and safety. Further, the actuator may have a brake mechanism built into the design of the unit, to thereby hold in place and stop the up or down movement of the device whenever power is no longer directed to the unit. 
         [0015]    A preferred method of construction of the invention includes an actuator driven pivoting stairway in which the stairway is manufactured using modular components. The use of modular a design permits the combination of multiple components from stock, pre-assembled sections to accommodate different installation requirements. A modular system offers greater flexibility in assembly, economical shipping, and increased safety in assembly due to the reduced weight of the modular components as compared to a single piece unit. Further, the modular design of the present invention allows in-field assembly to fit a full range of ceiling height measurements, without sacrificing the strong, stable, safe and secure integrity of the entire stairway unit. Alternatively, the ADPS may be completely or partially assembled without the use of modular components. 
         [0016]    The invention offers many benefits including, but not limited to, transforming vacant space into a usable storage or living area, offering additional access points to another floor, and freeing up floor space traditionally encumbered by a permanently located staircase. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of one embodiment of the actuator driven pivoting stairway (ADPS) system in the down, or usable position. This view illustrates that the top step may be level with the upper floor plane. 
           [0018]      FIG. 1A  is a perspective view of the system illustrated in  FIG. 1  and showing movement into the stowed position. 
           [0019]      FIG. 2  is a perspective view of the embodiment shown in  FIG. 1 , but illustrating the ADPS in the up or stowed position. 
           [0020]      FIG. 3  is a front view of the embodiment shown in  FIGS. 1 and 2 , and showing the ADPS in a down position, and illustrating a straight on-off access at an upper level. 
           [0021]      FIG. 4  is a perspective view of various modular elements for use in a preferred embodiment. 
           [0022]      FIG. 5  is an exploded view of an embodiment of the present invention 
           [0023]      FIG. 6  is an exploded view of an embodiment of a pivot bracket assembly mounting. 
           [0024]      FIG. 7  is an exploded view of an embodiment of an actuator rod pivot assembly. 
           [0025]      FIG. 8  is a fragmentary, partially exploded view of one embodiment of the actuator pivot mounting assembly. 
           [0026]      FIG. 9A  is a fragmentary, exploded view of one embodiment of a step rail assembly. 
           [0027]      FIG. 9B  is an enlarged, fragmentary view of a step profile. 
           [0028]      FIG. 10  is a perspective view of an alternative, articulated, actuator driven pivoting stairway (ADPS). 
           [0029]      FIG. 11  is a perspective view of the embodiment of  FIG. 10 , but showing the hand rail rotated into a collapsed position in readiness for segment rotation. 
           [0030]      FIG. 12  is a perspective view of the embodiment shown in  FIGS. 10 and 11 , but illustrating section rotation. 
           [0031]      FIG. 13  is a perspective view of the embodiment shown in  FIGS. 10-12 , but illustrating the system in the up or stowed position. 
           [0032]      FIG. 14  is a fragmentary, partially exploded view of an alternative embodiment of a stairway section, and showing an access panel and removable stair treads. 
           [0033]      FIG. 15  is an illustration of one embodiment of an outer panel assembly. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
       I. Stowable Stairway System 
       [0035]    The present invention may be generally described as a stairway system  10  to provide access between spaces on two or more different levels of a building or other multi-level structure. Specifically, the invention is directed to a stairway system  10  having means for retracting into the ceiling or floor  12  of a level. Means may include use of an actuator  14  as part of the system  10  (See  FIGS. 1 through 15 ). 
         [0036]    As will be apparent, the systems and methods of the present invention allow installation of the stairway system  10  without drilling of pivot holes in the existing floor joists or frame  16  at the top  18  of the stairway system  10 , as is required by known apparatuses. In a preferred embodiment of the invention, the stairway system  10  is pivoted at the elevated top end  18  (see for example  FIG. 1 , although it is to be appreciated that the stairway system  10  may be pivoted at the lower end  20  as well. The invention allows the stairway system  10  to be stored completely or partially into the ceiling or floor space  12 . It should be noted the invention could be designed to rest just below the ceiling or floor or above the ceiling or floor, should that be preferred. 
         [0037]    As may be observed particularly in the view of  FIG. 3 , a preferred embodiment of the stairway system  10  is designed such that the width W of the stairway system  10  fits between standard trusses or floor joists  16  that are set on a  24 ″ center. It should be noted however that the stairway system  10  may be designed to fit any desired opening width. 
         [0038]    As may be seen generally in  FIGS. 1 ,  1 A, and  2 , a preferred embodiment of the stairway system  10  includes a stairway  22 , an actuator  14  having a base end  24  and a rod end  26 , and a drive lever  28  pivotally connected to the rod end  26  of the actuator  14 . A driven pivot bracket  30  is adapted to be attached to the upper floor or framework  16  on one side of the stairway  22 , with a first end  32  being connected to the base end  24  of the actuator  14  and a second end  34  being attached to the drive lever  28 . A non-driven pivot bracket  36  is adapted to be attached to framework  16  on an opposite side of the stairway  22 . 
         [0039]    As mentioned, the systems and methods of the present invention allow installation without drilling of pivot holes in the existing floor joists or frame  16  at the top  18  of the stairway  10 . In contrast, a pivot rod  38  is seated in the pivot brackets  30 ,  36  located on each side of the stairway  22  opening (See  FIG. 6 ). Although the method of installation shown in the Figures is a preferred method, it is to be understood that other methods of installation may include attaching the stairway system  10  directly to the floor  12  above or to the frame members  16 . In its present form, the stairway system  10  allows the positioning of the stairway  22  between the ceiling trusses or floor joists  16 . 
         [0040]    With attention now to  FIG. 6 , the pivot assembly  40  may be seen. As illustrated, a preferred pivot assembly  40  may be mounted just below the top step  62  of the stairway  22 . As may be further observed, the pivot assembly  40  may include a pivot crosstie  42 , driven pivot bracket  30 , non-driven pivot bracket  36 , and drive lever  28 . The pivot crosstie  42  may be attached to a selected side rail  70  top  44  using brackets  46  as added support. The drive lever  28  may be mounted to the bracket  46  and the side rail top  44 . 
         [0041]    As shown, the non-driven pivot bracket  36  may be assembled though the brackets  46 , pivot crosstie  42 , side rail top  44  and the drive lever  28 , and connected to the driven pivot bracket  30 . 
         [0042]    In the present form of the invention, the stairway motion may be created by the use of an actuator  14 , such as the screw drive linear actuator shown. It should be noted that the actuator  14  could be of a design other than screw driven. The actuator  14  might be piston driven, it might be chain driven, it might be pneumatic in design, and it might be hydraulic in design, as non-limiting examples. A preferred actuator  14  includes a gear motor drive that rotates a screw rod (not shown) which is housed within the unit itself. As may be further observed with reference to  FIG. 7 , the drive unit may be attached to the drive lever  28  at the rod end  26  of the linear actuator  14  by use of a clevis type or suitable positive connector, such as direct couple, spring loaded connector, rigid connection, as non-limiting examples. As viewed in  FIG. 8 , the base end  24  of the actuator  14  may be connected by a pivot pin  50  and the pivot mounts  52  on the driven pivot bracket  30 . The actuator  14  may be further provided with means for manual operation, if desired. Access  90  for manual operation is shown in phantom. Although a preferred arrangement has been shown and described, it is to be understood that the actuator  14  could be installed in any manner that allows the connection of one end of the actuator to the framing or flooring, and the other end attached to the unit in such a manner as to afford the system  10  to operate correctly, as floor constructions may vary. 
         [0043]    With reference now to  FIG. 1A , system  10  operation may be viewed. The actuator  14  is extended in the direction of arrow A; the force pushes the drive lever  28  in the direction of arrow B away from the actuator base. This action rotates the pivot crosstie  42  (not seen in this view) and the rest of the pivot assembly  40  (see  FIG. 6 ) in the direction of arrow B. As the push force is applied to the drive lever  28  of the pivot assembly, the stairway  22  raises in the direction of arrow C to the upper or horizontal position as viewed in  FIG. 2 . To lower the stairway  22 , the actuator  14  is retracted; the pull force allows the pivot assembly  40  to rotate in the opposite direction, which thereby lowers the stairway  22  to the usable position shown in  FIG. 1 . When the system  10  is pivoted into the fully raised position illustrated in  FIG. 2 , the unit may then be parallel with the upper floor  12 . 
         [0044]    The actuator  14  may also be operated with a power supply enabling the unit to be operated with a battery (not shown) during a power outage situation, for example. 
         [0045]    A preferred embodiment may utilize a power supply consisting of a 12V DC motor  56  which is supplied current through a 120 V AC converter  54 . It should also be noted that the invention could be designed to operate on a variety of power systems such as 12V DC, 24 V DC, 120V AC, and 240 V AC, as non-limiting examples. Alternatively, power could be supplied and/or generated using other methods such as solar, hydroelectric, battery, and wind, as non-limiting examples. 
         [0046]    In a preferred embodiment of the system  10 , the actuator  14  may be provided with one or more of a breaking system, current load limits, as well as separate circuits for control operations. The stairway  22  may also be equipped with limit switches  58  for upper and lower stops as well as sensors for obstruction detection (not shown). 
         [0047]    As may be observed, the actuator  14  and drive lever  28  are preferably mounted to one side of the stairway  22  step area, giving the user a clear and straight approach to the steps  60 . Further, the top step  62  may be easily exited or entered from the upper level floor, and all steps  60  may be large enough to provide for easy and comfortable use. 
         [0048]    It is preferred that the present system  10  be primarily fabricated with extruded, modular aluminum metal parts. The illustration of  FIG. 4  shows various interchangeable stairway  22  lengths that may be used with the system top section  64  and bottom section  66 . Although extruded aluminum is the preferred material, it should be noted that other types of materials, sufficient to withstand the stresses inherent in its use and design, may be used in the construction of the invention such as plastic, resins, other metals, composites, and woods or other natural materials, as non-limiting examples. 
         [0049]    As seen generally in  FIGS. 1-3  and  5 , the stairway  22  may be equipped with handrails  68  on one or both sides.  FIG. 5  illustrated the manner by which the handrail  68  may be attached to selected side rail sections  70 . Since the present system  10  allows straight on and off of the stairway  22 , the handrail  68  may be mounted on either side, or both sides of the stairway  22 , without causing any obstruction or safety hazard. The handrail  68  is preferably made of tubular metal that is mounted to the stairway  22  for personal safety; however the handrail  68  may be manufactured from different materials such as plastic, composites, solid metal, wood, etc, and may be mounted in different locations. Further, the handrail  68  may be constructed in other configurations than tubular, such as flat, and square, as non-limiting examples. 
         [0050]    The present system  10  allows the handrail  68  remain attached to the stairway  22  even while in the upper, stowed position (See  FIG. 2 ). Thus, the handrail  68  does not need to be collapsed or folded out of the way, as is required by other known handrail assemblies. Although it should be noted that the handrail  68  may be designed in such a manner as to be folded, collapsed, or in other manner retracted, if desired. 
         [0051]    The present system  10  may also include a fire proof cover material on a bottom surface  72  of the stairway unit (see  FIG. 15 ). Fire proof material can be, but is not limited to, drywall, metal or other suitable materials that also allow the user to paint, texture, or otherwise match the surface finish to create an eye pleasing structure that may compliment the existing ceiling surface. The system may further be provided with a pre-installed fire brush  74 . As may be observed particularly in  FIG. 1 , a fire brush  74  may be used to create a fire stop surface between the upper and lower floors  12  at the stairway opening  76 . It should be noted that although the present drawings illustrate use of a fire brush  74 , any type of fire resistant material which meets local building codes and which fills the space along the sides of the stairway opening  76  may be used, such as an interlocking magnetic material, flexible plastic or other suitable material, or fabric buffer, as non-limiting examples. 
         [0052]    The present system  10  may be equipped with leveling devices  78  on the bottom section  66  of the stairway  22  that rest against the floor to allow for uneven surfaces when the stairway  22  is in the lowered position. These leveling devices  78  may be designed to incorporate one or more of limit switches, safety stops, and operation warning lights, as non-limiting examples. 
       II. System Controls 
       [0053]    The control for the present invention may be mounted off the stairway unit  22  and may be wired to the actuator  14  via a whip or wire type cord  80  connection. A preferred control operator in the form of a removable momentary key operated switch  82  may be seen in  FIGS. 1 ,  1 A, and  2 . The preferred switch  82  is designed to be activated and operator attended for system  10  and stairway  22  operation, to thereby prevent unintentional movement of the stairway  22 . Use of the removable key ensures that the operator can control by whom and when the stairway  22  is used. Although this switch is preferred, other types and configurations of control units could be employed, such as pushbutton, push-pull, and lever controls, and electronic, wireless remote control, audio recognition, and optical communication, as non-limiting examples. 
       III. Modular Design 
       [0054]    As discussed previously and shown in  FIGS. 4 and 5 , the present invention may be designed in modular sections. The modular design may incorporate fabricated stock parts. The steps  60 , brackets  46 , side rails  70 , joint plates  84 , covers  86 , end caps  88 , and additional sub assemblies may be designed as bolt together assemblies. Although modular construction is preferred for its ease of use and efficiency, the system  10  may be assembled using glue, rivets, thermal welding, electronic welding, sonic welding, or fused together with light energy, for example. 
         [0055]    The contemplated modular construction of the present system  10  provides manufacturing and installation advantages. For example, rather than one solid welded stairway  22  that must be custom built to each installation, the modular design may use preassembled sections that can be assembled in the field to allow a full range of sizes and installation options. In addition, the modular design of the present invention reduces assembly, shipping, and handling costs as compared to one piece units. It should be noted however, that the present invention is not limited to modular construction and may be manufactured without the use of modular components. It may be built on site or it may be built in one piece and transported to the installation location. The present system  10  may be entirely custom fabricated. 
       IV. Articulated System 
       [0056]    With attention to  FIGS. 10-13 , an articulated stairway system  10 A may be seen. As may be observed, the stairway system  10 A may be provided with hinges  92  or other acceptable means to thereby hingedly connect adjacent stairway sections  22 . The articulated design permits the unit  10 A to be collapsed prior to retraction into the stairway opening. The unique collapsible design allows the system  10 A to be stowed into a stairway opening  76  having a length L less than the total, extended stairway length L′(see  FIG. 13 ). This capability frees up floor space on the upper level and provides a more compact storage unit. 
         [0057]    As seen particularly in  FIG. 10 , the articulated system  10 A may include a top section  64  a bottom section  66  and at least two stairway sections  22 . The stairway sections  22  are pivotally connected in an acceptable manner, as by the hinges  92  shown, for example. The hinges  92  may be provided with suitable locking mechanisms  94  to safely retain the stairway sections  22  in the extended position while in use. A handrail  68  may be optionally provided. 
         [0058]    A method of stowing the articulated system  10 A may be seen in  FIGS. 11-13 . As shown, and if provided with handrails  68 , handrails  68  are moved in the direction of arrows D to rest against the stairway sections  22 . As seen in  FIGS. 12 and 13 , stairway section  22  is rotated in the direction of arrow E to a position to overlay section  22 . The stacked unit is then rotated in the manner previously described, into the stairway opening  76 .  FIG. 13  illustrates the articulated system  10 A in the stowed position and shows the relative economy of storage length, with length L being shorter than L′, the total extended length. 
       V. Methods of Use 
       [0059]    In use, the both the articulated and non-articulated systems  10 ,  10 A may be operated in a variety of ways with user controls, as previously described. When the operator desires to lower the stairway  22 , a removable key (not shown) may be inserted into the control switch  82 . The key may be turned to provide a control signal to the actuator  14 . The actuator  14  then provides the force to the drive lever  28 , and the stairway  22  pivots upward or downward. 
         [0060]    Sensors and other devices, as previously described, may be automatically activated during the raising and lowering process to control the safe and accurate raising and lowering of the stairs. Once down, the stairway may be used. The process may be reversed to raise the stairway to the stowed position. 
       VI. Methods of Installation 
       [0061]    The ADPS may be configured to be installed in a variety of configurations, depending on the installation area, and may be installed in new construction, or after construction is complete (i.e., retrofit). The following example describes methods of installation for a retrofit application: 
         [0062]    Selecting a location for installation; removing an area of ceiling sufficient for the system  10 ,  10 A; mounting the pivot assembly  40  to the floor joists  16 ; coupling modular sections  22 ,  64 ,  66  of the stairway  22  together in a predetermined manner and sufficient in height to reach from the ceiling to the floor at the desired angle; coupling the assembled stairway  22  to the pivot frame assembly  40 ; mounting the actuator  14  and driven pivot bracket  30  to the joist  16  and to the drive lever  28 ; and coupling the control system to a power source, and to the actuator assembly. 
         [0063]    The systems  10 ,  10 A of the present invention may be further provided with a modified top section  64 A. Modified top section  64 A is adapted to permit emergency access to the upper level in the event of power or other mechanical system failure. As seen in  FIGS. 14 and 15 , the modified top section  64 A may include a removable panel  94 , to thereby allow access to treads  60 . Treads  60  are attached to side rails  70  by way of accessible bolts  98  which may be unfastened to thereby remove treads  60  from section  64 A. Access through the top section  64 A is then possible. 
         [0064]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.