US20060277848A1

US20060277848A1 - Telescoping stairway for accessing attic storage space

Info

Publication number: US20060277848A1
Application number: US11/153,763
Authority: US
Inventors: Jay Penn
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-14
Filing date: 2005-06-14
Publication date: 2006-12-14

Abstract

A stairway for use in an opening formed between an attic and a floor below comprises a frame adapted to fixedly engage the opening and a plurality of stairway sections operatively coupled to the frame. The stairway sections each have a pair of rails and a plurality of steps coupled between the respective rails. The rails further comprise respective upper and lower edge surfaces having corresponding shapes to permit nesting engagement of the stairway sections on top of each other and relative parallel movement of the stairway sections with respect to each other. Successive ones of the stairway sections are operatively coupled to each other such that they remain nested while being moved relative to each other. Upon reaching an extent of travel relative to each other, orientation of the successive ones of the stairway sections changes to a substantially contiguous and axially aligned structure in which the successive stairway sections are linked end-to-end to provide a continuous stairway. One or more locking pins may be adapted to lock the successive stairway sections in an end-to-end configuration.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to foldable stairs configured for installation in an opening between floors of a structure, such as an attic stairway, or more particularly, to an easily deployable stairway that permits access to an attic space located above a garage or living quarters.
2. Description of Related Art
Many homes have attic spaces above garages and living quarters, and these attic spaces often provide a storage location for various items. While some attic spaces are finished and have access via a fixed stairway, most attic spaces remain unfinished and have more rudimentary access systems. The most basic access system is a simple opening or scuttle hole formed in the ceiling dividing the attic space from the room below. The scuttle hole is often located above a closet or hallway, and may be covered by a hatch that comprises a removable portion of ceiling, such as formed from plywood or drywall. A user would position a ladder below the opening and access the storage space by climbing through the scuttle hole.
An improvement over this basic access system is a pull-down or fold-down ladder or stairway that is permanently coupled to a hingedly attached door covering the opening. The pull-down stairway may be folded into a plurality of sections to provide a generally compact structure when stowed. The user opens the door and unfolds the stairway to bring it into an operational position. This pull-down stairway provides improved convenience since the user does not have to transport a ladder to and from the access location, and the stairway is anchored to the opening to thereby provide an increased degree of safety for the user. When the stairway is stowed, it does not take up any floor space in the room below, in contrast to fixed stairways that take up substantial space.
A drawback of fold-down stairways is that they can be very cumbersome, difficult and unsafe to deploy. Depending upon the height of the ceiling, the folded stairway sections may be out of reach for many users unless another ladder or step stool is used. The user must unfold the stairway by pivoting a substantial portion of its mass while reaching upward often well above the user's head. If the user does not maintain a firm grip on the stairway as it unfolds, the unfolded stairway portions could inadvertently swing downward and strike the user with significant force. To return the stairway to the stowed position following use, the user repeats the same procedure in reverse. These disadvantages make the use of fold-down stairways impractical and undesirable for many users, particularly older homeowners and women that lack height and sufficient upper body strength.
Thus, it would be advantageous to provide an improved way to deploy an attic stairway easily and safely, while avoiding the disadvantages of conventional fold-down attic stairways.

SUMMARY OF THE INVENTION

The invention overcomes the disadvantages of conventional fold-down attic stairways by providing a telescoping stairway that deploys without unfolding. Instead, the stairway includes plural sections that remain nested while stowed, and deploy by extending axially with respect to each other and link end-to-end to provide a continuous stairway.
More particularly, an exemplary stairway for use in an opening formed between an attic and a floor below comprises a frame adapted to fixedly engage the opening and a plurality of stairway sections operatively coupled to the frame. The stairway sections each have a pair of rails and a plurality of steps coupled between the respective rails. The rails further comprise respective upper and lower edge surfaces having corresponding shapes to permit nesting engagement of the stairway sections on top of each other and relative parallel movement of the stairway sections with respect to each other. Successive ones of the stairway sections are operatively coupled to each other such that they remain nested while being moved relative to each other. Upon reaching an extent of travel relative to each other, orientation of the successive ones of the stairway sections changes to a substantially contiguous and axially aligned structure in which the successive stairway sections are linked end-to-end to provide a continuous stairway. A locking pin may be adapted to lock the successive stairway sections in an end-to-end configuration.
In an embodiment of the invention, the rails of at least one of the stairway sections further include a slot extending substantially an entire length of each associated one of the rails. A slide block is adapted to travel within the slot of a corresponding one of the rails, and a pair of parallel linkages coupled between the slide block and a corresponding one of the rails of a successive one of the stairway sections. The parallel linkages are oriented in a first direction when the successive stairway sections are nested relative to each other and in a second, substantially perpendicular, direction when the successive stairway sections are joined. The pair of parallel linkages may also be are vertically offset with respect to each other. At least one locking pin may be adapted to lock at least one of the parallel linkages in the second direction. The slide block may further include at least one roller adapted to engage the slot to facilitate low friction movement of the slide block within the slot.
In another embodiment of the invention, a door is hingedly attached to the frame with at least a first one of the stairway sections being fixedly coupled to the door. A locking finger is operatively coupled to the frame and oriented to engage a corresponding opening of the door to thereby lock the door in a closed position when the stairway sections are stowed. A manual release lever may be adapted to disengage the locking finger from the opening. Alternatively, a release cable may be adapted to disengage the locking finger from the opening upon deployment of the stairway sections.
In another embodiment of the invention, at least one slider rail is coupled to the first one of the stairway sections. The frame further comprises a pivot point that slidably engages the at least one slider rail, wherein the slider rail defines a range of motion of the plurality of stairway sections in pivoting from a substantially horizontal stowed orientation to a deployed orientation disposed at a predetermined angle from horizontal. The slider rail may further comprise an end stop defining a limit of travel of the slider rail with respect to the pivot point. The slider rail may further comprise a temporary stop prior to the end stop defining an initial angle for deployment of the stairway sections prior to coming into contact with the floor.
In yet another embodiment of the invention, at least one deployment cable is associated with each rail of the plurality of stairway sections. The deployment cable controls relative movement of the plurality of stairway sections such that relative movement in a stairway deployment direction is provided by paying out the deployment cable and relative movement in a stairway stowing direction is provided by retracting the deployment cable. A rotatable drive screw carrying at least one pulley is engaged with the. Rotation of the drive screw in a first direction provides paying out of the deployment cable and rotation of the drive screw in a second direction provides retraction of the deployment cable. An electric motor may be operatively coupled to the drive screw to enable powered rotation of the drive screw in either the first or second directions. The electric motor and the drive screw may be coupled to the frame, or may be disposed within at least one of the plurality of stairway sections. Alternatively, a removable crank may be adapted to be operatively coupled to the drive screw to enable manual rotation of the drive screw. A pull rope may also be operatively coupled to the drive screw to enable manual rotation of the drive screw. The pull rope may be adapted to retract when not in use, with a removable hook adapted to retrieve the pull rope when retracted.
In still another embodiment of the invention, the upper edge surfaces of the plurality of stairway sections further comprise a generally convex rounded shape, and the lower edge surfaces of the plurality of stairway sections further comprises a generally concave rounded shaped adapted to nest with the generally convex rounded shape of the upper edge surfaces. The lower edge surfaces of at least one of the plurality of stairway sections may further comprises at least one roller adapted to enable low friction sliding engagement between successive ones of the stairway sections.
A more complete understanding of the telescoping stairway will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings, which will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of the axially extending stairway in a stowed position;
FIG. 2 is side view of the stowed stairway taken through the section 2-2 of FIG. 1;
FIGS. 3A-3F are side sectional views of the stairway deployment sequence;
FIG. 4A is a side view of an exemplary drive mechanism for the stairway;
FIGS. 4B1-4B3 are views of an exemplary manual drive mechanism for the stairway, in which FIG. 4B 1 is a side view, FIG. 4B 2 is a partial bottom view, and FIG. 4B 3 shows a drive handle;
FIGS. 4C1-4C2 are side views of another exemplary manual drive mechanism for the stairway, in which FIG. 4C 1 is a side view and FIG. 4C 2 shows a rope hook;
FIGS. 4D1-4D2 are top views of a drive mechanism as shown in FIG. 4A;
FIG. 5 is a side view of the coupling between the stairway sections;
FIGS. 6A and 6C are views showing one of the stairway section rails, and FIG. 6B is an end sectional view showing the interior of one of the ladder rails;
FIG. 7 is a side sectional view of two overlapping stairway sections;
FIG. 8 is an end sectional view of three overlapping stairway sections;
FIG. 9 is an end sectional view of one of the stairway sections showing a locking mechanism for locking two stairway sections together;
FIG. 10 is a side sectional view as taken through the section 10-10 of FIG. 9;
FIGS. 11A-11C are partial views of the first stairway section showing the pivot mount block;
FIG. 12 is a top sectional view of the first stairway section rail;
FIG. 13 is a top sectional view of the second stairway section rail;
FIG. 14 is side sectional view of an alternative embodiment of the first stairway section rail;
FIG. 15 is side sectional view of an alternative embodiment of the second stairway section rail;
FIGS. 16A-16B are sectional side and perspective views of an end cap for the first and second stairway section rails showing an alternative locking mechanism, FIG. 16C is an end sectional view, and FIG. 16D shows a perspective view of the plunger and bolt;
FIG. 17 is a perspective view of an alternative mating end cap for the second and third stairway sections;
FIGS. 18A-18B are partial side sectional views of the slider rail release mechanism, and FIG. 18C in an end sectional view;
FIG. 19 is a side sectional view of an exemplary door release mechanism;
FIGS. 20A-20C are partial sectional views of an alternative stairway deployment mechanism;
FIGS. 21A-21C are partial sectional views of an alternative embodiment of the slide block;
FIGS. 22A-22C are partial side and sectional views of an exemplary handrail for the stairway sections;
FIG. 23 is a side view of a slider block tether release mechanism; and
FIG. 24 is a side view of an adjustable foot for the third stairway section.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention satisfies the need for an attic stairway that can be deployed safely and easily without the drawbacks of the conventional fold-down attic stairways. In the detailed description that follows, like element numerals are used to describe like elements illustrated in one or more figures.
Referring first to FIGS. 1-2, an exemplary attic stairway is shown in accordance with an embodiment of the invention. The exemplary attic stairway includes a mounting frame 10 formed in a generally rectangular shape having transverse ends and side members. The mounting frame 10 may be comprised of any suitable material, such as wood, plastic, metal or other high strength, lightweight material capable of supporting a suitable load carried by the stairway. In a preferred embodiment, the mounting frame 10 is comprised of a continuous metal strip formed in the appropriate shape and joined at the ends to form a rectangular loop. The mounting frame 10 provides a mechanical structure that supports the other functional components of the attic stairway and provides a surface for mounting the attic stairway into a scuttle hole of an attic space (as will be further described below). The scuttle hole is a rectangular opening in the attic floor defined between adjacent joists 201 and headers 203. Drywall 202 coupled to the undersides of the joists 201 and headers 203 defines the ceiling of the room below. The mounting frame 10 is securely coupled to the joists 201 and headers 203, such as using nails, lag screws, and the like. The mounting frame 10 may further include a lip that provides a seal with the scuttle hole and that also provides a decorative border framing the scuttle hole.
The mounting frame 10 carries a plurality of stacked stairway sections. As best shown in FIG. 2, the stairway sections include a first stairway section 111, a second stairway section 121, and a third stairway section 131. Each stairway section includes a pair of side rails joined by a plurality of steps 114. While in the stowed position, the stairway sections are nested in engagement with each other. The first stairway section 111 is coupled to door 15 using pivot joints 117, which is in turn affixed to the mounting frame 10 via hinge 14. During normal operation, the pivot joints 117 remain locked in the position shown in FIG. 2, i.e., normal to the door 15. The door 15 may be comprised of wood, plastic, metal or other suitable material. As will be further described below, the door 15 pivots downward as the stairway sections deploy. The door 15 may further include a latch that locks the door 15 in a closed position, i.e., substantially flush with the ceiling.
In an embodiment of the invention, the steps 114 may be adapted to snap or bolt into ladder sections 111, 121, and 131. To minimize space required for shipping, it is anticipated that the steps be left unattached to the ladder sections. The ladder sections 111, 121, and 131 would be folded by 90° from its normal (installed) operating position so as to lay parallel to the plane of the door 15 by use of rotating stowage pivot 151. Alternately, stowage pivot 151 could be substituted for a snap-in joint between the door 15 and ladder section 111 to provide improved packaging efficiency during shipping.
The stairway sections are coupled together by a plurality of slide linkages. As best shown in FIG. 2, first and second stairway sections 111, 121 are coupled by a pair of parallel linkages 113. The linkages 113 are rotationally coupled at a first end thereof to a corresponding end of the second stairway section 121, and are rotationally coupled at a second end thereof to a slide block 112. The slide block 112 is disposed in a corresponding slot that runs the length of the first stairway section 111. Similarly, second and third stairway sections 121, 131 are coupled by a pair of parallel linkages 123. The linkages 123 are rotationally coupled at a first end thereof to a corresponding end of the third stairway section 131, and are rotationally coupled at a second end thereof to a slide block 122. The slide block 122 is disposed in a corresponding slot that runs the length of the second stairway section 121. Identical slide linkages are located on the other side of the stairway sections (see FIG. 1). The movement and operation of the slide linkages will be described in further detail below.
Referring briefly to FIG. 5, the coupling between the staircase sections 111, 121, 131 is shown in further detail. First and second stairway sections 111, 121 are axially aligned with the linkages 113 rotated parallel to the stairway sections. The slide block 112 is located at the end of the slot corresponding to the lowermost end of second stairway section 121. Second and third stairway sections 121, 131 are nested on top of each other with the linkages 123 rotated perpendicular to the stairway sections. The slide block 122 is located at the end of the slot corresponding to the uppermost end of second stairway section 121. In an embodiment of the invention, one of linkages 113 includes an aperture 126 that is aligned with a corresponding pin 127 that forms part of slide block 112. The pin 127 enters the aperture 126 when the first and second stairway sections 111, 121 become axially aligned. Similarly, one of linkages 123 includes an aperture 124 that is aligned with a corresponding pin 125 that forms part of slide block 122. The pin may be electrically or mechanically actuated to lock the ladder sections in the deployed configuration. The second stairway section 121 may further include a stop 140 comprising a pin having a head that comes into contact with a corresponding surface of the first stairway section 112. The stop 140 prevents over rotation of the second stairway section 122 relative to the first stairway section 112.
In an embodiment of the invention, the stairway sections are deployed by a drive mechanism that includes drive motor 11, drive screw 21, pulleys 16, 26 and cables 18, 19 (see FIGS. 1 and 2). The drive motor 11 is mounted to the frame 10 and rotationally drives the drive screw 21. Bracket 12 encloses drive motor 11 and has an opening to permit drive screw 21 to extend therethrough. Thrust bearing 13 is radially coupled to drive screw 21 and is oriented to contact the surface of bracket 12. A pulley adjust nut 22 is threadingly engaged with the drive screw 21 such that the pulley adjust nut moves axially along the length of the drive screw 21 as the drive screw rotates. Pulley adjust nut bracket 24 is carried by the pulley adjust nut 22, and in turn carries a plurality of adjusting pulleys 26. As will be further described below, the plurality of adjusting pulleys 26 are substantially vertically aligned and share a common axial shaft 25 that is split into two sections to avoid interference with drive screw 21, so that in FIG. 1 they appear as a single pulley. Similarly, cable lengthening pulleys 16 are disposed at a first side of frame 10 and cable guide pulley 17 is disposed at a second side of the frame. As with the adjusting pulleys 26, the cable lengthening pulleys 16 are vertically aligned and share a common axial shaft 20 (see, e.g., FIG. 2). Pulley 17 is horizontally aligned with the uppermost one of pulleys 16. Cable 18 extends through selected ones of the pulleys 16, 26 at a first side of the ladder structure, and cable 19 extends to a second side of the ladder structure. The drive mechanism controls the paying out of cables 18, 19, which in turn enables the deployment of the stairway sections.
The exemplary deployment sequence for the stairway sections is illustrated in FIGS. 3A-3F. In FIG. 3A, the stairway is shown in the fully stowed position. The three stairway sections 111, 121, 131 are stacked as described above with respect to FIG. 2. In FIG. 3B, the drive mechanism causes the drive screw 21 to rotate counterclockwise, causing the tension to increase in the cables 18, 19 (e.g., greater than 75 pounds) and thereby release the door latch. The weight of the stairway sections then cause the door 15 to pivot downward. The drive mechanism causes the drive screw 21 to rotate clockwise, allowing the cables 18, 19 to pay out, thereby positioning the three stairway sections 111, 121, 131 at an angle with respect to the floor below. The tension in the cables 18, 19 is greatest when the door 15 is horizontal, and drops to minimum when the door 15 and the first ladder section 111 is fully deployed (e.g., approximately 27° from vertical).
Each of the stairway sections include corresponding deployment cables. Each of these corresponding deploying cables are in communication with and also exert tension on cables 18 and 19. The tension that each of the corresponding deployment cables exerts on cables 18 and 19 determines the deployment sequence, such that whichever set of cables corresponding to a section of the ladder currently exerts the higher tension on cables 18 and 19 will deploy and the other ladder sections will remain in their relative positions. In FIG. 3C, as the door 15 and first ladder section 111 rotates downward, the tension in cables 18 and 19 caused by in the second stairway section deployment cables exceeds that exerted by the first ladder section 111. This causes the uppermost two stairway sections 121, 131 to slide downward together with respect to the first stairway section 111, which remains fixed to the door 15. The two stairway sections 121, 131 continue to slide the length of the first stairway section 111, until eventually the first and second stairway sections 111, 121 join together at respective ends as shown in FIG. 3D. As will be further described below, a locking mechanism fixes the orientation of stairway sections 111, 121 with respect to each other so that they form a contiguous rail.
In FIG. 3D, once stairway sections 111 and 121 are in deployed position with respect to each other, the tension that the third stairway section 131 exerts on deployment cables 18 and 19 becomes greater than the tension caused by the second stairway section, causing the third stairway section 131 to slide downward with respect to the second stairway section 121. The third stairway section 131 continues to deploy with respect to the second stairway section 121 until the second and third stairway sections 121, 131 join together at respective ends as shown in FIG. 3E. A similar locking mechanism rigidly fixes stairway sections 121, 131 so that now the first, second and third ladder sections form a contiguous rail. After stairway sections 121, 131 are joined, the tension in cables 18, 19 due to stairway section 131 decreases such that the first stairway section 111 exerts the largest force on cables 18 and 19. This causes the angle of the fully deployed stairway with respect to the floor to once again increase. The entire stairway continues to pivot around the axis defined by the hinge 14, until the bottom of the third stairway section 131 comes to rest with the floor, as shown in FIG. 3F. To stow the stairway following deployment, the above sequence is reversed.
Referring now to FIG. 4A (side view) and FIGS. 4D1-4D2 (top views), an exemplary drive mechanism is shown in greater detail. Cable 19 originates at the center of a first cable lengthening pulley 16A and is routed around first adjusting pulley 26A, then back around the first cable lengthening pulley 16A, then to a second one of the adjusting pulleys 26B, then back again to a second cable lengthening pulley 16B, and then all the way across the structure to cable guide pulley 17. After passing cable guide pulley 17, cable 19 is redirected parallel to the side of the frame 10 (see FIG. 1). Cable 18 originates at the center of a third cable lengthening pulley 16C and is routed around third adjusting pulley 26C, then back around the third cable lengthening pulley 16C, then to a fourth one of the adjusting pulleys 26D, then back again to a fourth cable lengthening pulley 16D, and then redirected parallel to the opposite side of the frame 10 (see FIG. 1). In FIGS. 4D1-4D2, cable lengthening pulleys 16A-16D are illustrated in staggered form for convenience of illustration and explanation, but it should be appreciated that the pulleys all share a common axis 20 (as shown in FIG. 4A). Similarly, in FIGS. 4D1-4D2, adjusting pulleys 26A-26D are illustrated in staggered form for convenience of illustration and explanation, but it should be appreciated that the pulleys all share a common axis 25 (as shown in FIG. 4A).
With the pulley adjust nut bracket 24 disposed at a right side of the drive screw 21 (as seen in FIG. 4A), a substantial amount of the slack in cables 18, 19 is taken up by the multiple cable paths between the adjusting pulleys 26 and the cable lengthening pulleys 16. When the drive motor 11 causes the drive screw 21 to rotate in a clockwise direction, the pulley adjust nut bracket 24 moves to the left (as seen in FIG. 4A), causing the slack in cables 18, 19 to pay out. Thus, the drive mechanism produces an extension of cables 18, 19 by a distance that is a multiple of the corresponding movement of the pulley adjust nut bracket 24. In the embodiment of the invention shown in FIGS. 4D1-4D2, a four-times multiple of the cable length is achieved. It should be appreciated that greater or smaller multiple cable length extensions could be achieved by increasing or decreasing the number of pulleys.
Returning to FIGS. 1 and 2, a slider rail 116 is pivotably coupled at a first end to a post 152 that is mounted on pivot mount block 150 that is also affixed to the first stairway section 111. The slider rail 116 is movable in an axial direction relative to a slider 339 that remains pivotably fixed to the frame 10. A first deployment pulley 119 is coupled to the slider 339, and a second deployment pulley 120 is coupled to an end of the slider rail 116. The cable 19 extends from the drive mechanism (discussed above) to the first deployment pulley 119 and redirected to the second deployment pulley 120. Thereafter, the cable 19 extends back along the first stairway section 111 and terminates as will be further described below. Cable 18 follows a similar path on the other side of the stairway sections. As shown in FIGS. 3A, 3B, as the slack in the cables 18, 19 increases due to operation of the drive mechanism, the distance between the two deployment pulleys 119, 120 increases with the slider rail 116 moving axially with respect to the slider 339. As a result, the door 15 pivots downward, thereby positioning the three stairway sections 111, 121, 131 at an angle with respect to the floor below.
An alternative embodiment of the drive mechanism is shown in FIGS. 4B1-4B4. As shown in FIG. 4B 1, the motor 11 is replaced with a gearbox 27 that includes a first helical gear 28 axially coupled to drive screw 21, and second helical gear 29 in mesh with the first helical gear. The second helical gear 29 is axially coupled to a manual drive shaft 30 having a receptacle 31. The receptacle 31 extends through the door 15 and is substantially enclosed by dust cover 32. FIG. 4B 2 shows the receptacle 31 from bottom view as including a female key sleeve. FIG. 4B 3 shows a suitable crank tool 33 having a male key end 34 (see also FIG. 4B 4) having a shape adapted to engage the female key sleeve. The crank tool 33 may further include crank handles 35 facilitating manual rotation of the male key end 34 upon engagement with the female key sleeve of receptacle 31. Rotation of the manual drive shaft 30 thereby produces corresponding rotation of the drive screw 21 to thereby pay out the cables 18, 19 in the same manner as described above. A user may thereby enable manual deployment of the stairway sections either instead of the motor controlled embodiment of FIG. 4A, or as a back-up system to operate the stairway in the event of loss of electrical power. It should be evident that a modified drive arrangement will allow either the motor or the manual shaft to drive the deployment in the same device.
Another alternative embodiment of the drive mechanism is shown in FIGS. 4C1-4C2. As in the preceding embodiment, the motor 11 is replaced with a deploy spool 40 and a stow spool 44 each axially coupled to the drive screw 21. A length of rope 45 has ends wound onto each of the spools 40, 44, forming a loop of rope that passes through an opening in the door 15. An internal spring 42 coupled to the deploy spool 40 within a bracket 43 causes the deploy spool to wind up the excess rope. By pulling the rope in a first direction, the deploy spool 40 can be caused to rotate the drive screw 21 and thereby pay out the cables 18, 19 in the same manner as described above, with the excess rope winding onto the stow spool. The stairway can be stowed by pulling the rope in the opposite direction. When not in use, the rope will wind onto the deploy spool 40 by operation of the internal spring 42. The door 15 is provided with an indentation 46 that permits capture of the rope using a suitable hook 47 when it is desired to deploy the stairway. Although not shown, it should be evident to those skilled in the art that the rope driven drive mechanism could be combined with a clutch arrangement such that the rope can drive the shaft but not vice versa. This allows the rope to function as a backup drive mechanism to deploy the stairway.
Referring now to FIGS. 6A-6C, the first stairway section 111 is shown in greater detail. FIG. 6A shows a section of a side view of the first stairway section 111 having an axially extending slot in which the slide block 112 travels (as discussed above). FIG. 6B shows an end view of one side rail of the first stairway section 111 in cross-section as having a rounded top and a generally hollow structure. The side rails of each stairway section would have generally similar construction and may be formed from extruded aluminum or like materials. The slide block 112 includes a rounded edge at upper and lower interior edges that is enclosed by upper and lower lips of the first stairway section 111, thereby holding the slide block within the axial slot. Linkages 113 are rotatably coupled to the slide block by pins 154. As discussed above, the cable 19 passes pulley 120 and is guided into the interior of first stairways section 111 by two successive guide pulleys 163, 165 to a termination point at the back of clevis 168. Clevis 168 has a shaft 162 that carries pulleys 160, 161 (described in more detail below). FIG. 6C shows a side view of the first stairway section 111, including the path of cable 19 as it passes pulley 120. Pulley 163 is mounted in an opening of the side of first stairway section 111, and guides cable 19 into the interior of the structure. Pulley 165 is disposed inside the structure of the first stairway section 111, and guides the cable 19 to the clevis 168 as discussed above.
FIG. 7 shows the interior construction of the side rails of the first and second stairway section 111, 121 as taken through a side sectional view. As discussed above, the cable 19 passes pulley 120 and is guided into the interior of first stairway section side rail by two successive guide pulleys 163, 165 to a termination point 168 at the back of clevis 167. Pulleys 163, 165 rotate on respective shafts 164, 166, which are each in turn fixed to the interior structure of the first stairway section 111. Clevis 167 carries pulleys 160, 161, which are aligned axially on shaft 162. The pulleys 160, 161 control the slack of a second cable 109 that enables the deployment of the second stairway section 121. The first stairway section 111 side rail further includes pulleys 175, 177 carried by respective shafts 176, 179 that are mounted to the interior of the side rail of first stairway section 111. Cable 109 originates at pulley 177, then passes around pulley 160, then back around pulley 177, then to pulley 162, then to pulley 175. Thereafter, the cable 109 exits through an opening in the body of the first stairway section side rail and enters a corresponding opening of the second stairway section side rail. Thus, as the slack in cable 19 is increased due to operation of the drive mechanism (described above), pulley 161 moves closer to pulleys 175, 177, thereby increasing the slack of cable 109 exiting from first stairway section 111.
As with the drive mechanism discussed above, the arrangement of pulleys provides an extension of cable 109 by a distance that is a multiple of the corresponding movement of the clevis 168. In the embodiment of the invention shown in FIG. 7, a four-times multiple of the cable length is achieved. As will be further described below, the extension of cable 109 permits the second stairway section 121 to deploy laterally by force of gravity with respect to the first stairway section 111, while the first stairway section 111 remains fixed to the door 15.
The second stairway section 121 includes a similar arrangement of pulleys and cables. After cable 109 enters the opening in the second stairway section 121, the cable 109 is guided into the interior of the stairway section 121 by guide pulley 186 to a termination point 193 at the back of clevis 192. Pulley 186 rotates on shaft 190, which is fixed to the interior structure of the second stairway section 121. Clevis 192 carries pulley 187 on shaft 191. Pulley 187 controls the slack of a third cable 209 that enables the deployment of the third stairway section 131. The second stairway section 121 further includes pulleys 188, 189 carried by respective shafts 195, 210. Shaft 195 is movable in a slot 197 against a bias provided by tension in the cables. The shaft 210 is fixed to the interior of second stairway section 121. Cable 209 originates at movable shaft 195, then passes around pulley 187, then back around pulley 188, then to pulley 189. Thereafter, the cable 209 exits through an opening in the body of the second stairway section 121 and enters a corresponding opening of third stairway section 131. Thus, as the payout of cable 109 is increased, pulley 187 moves closer to pulley 188, thereby increasing the payout of cable 209 exiting from second stairway section 121. The movable shaft 195 is further coupled to cable 182, that controls a release of a locking mechanism that couples the first and second stairway sections 111, 121 together (described below).
The arrangement of pulleys in the second stairway section 121 provides an extension of cable 209 by a distance that is a multiple of the corresponding movement of the clevis 192. In the embodiment of the invention shown in FIG. 7, a two-times multiple of the cable length is achieved. As will be further described below, the extension of cable 209 permits the third stairway section 131 to deploy laterally by force of gravity with respect to the second stairway section 121. The cable 209 terminates at an end point 198 of the third stairway section 131. A separate cable 199 provides a release of a locking mechanism that couples the second and third stairway sections 121, 131 together (described below).
FIG. 8 shows an end view of the interior construction of the side rails of the stairway sections 111, 121, 131 in a stacked configuration. The stairway sections are nested on top of each other, with each having a rounded convex top surface and a rounded concave bottom surface. Openings at the top surfaces of the stairway sections permits the cable to pass from one stairway section to another.
FIGS. 9 and 10 illustrate an embodiment of the locking mechanism for one of the stairway sections. As discussed above with respect to FIG. 5, slide block 122 travels within the axial channel formed in the side of the stairway section side rail. The slide block 122 includes an aperture in which a locking pin 127 can extend. The locking pin 127 is pivotally coupled to a rod 213 using shaft 225. The other end of rod 213 is pivotally coupled to the interior surface of the stairway section using shaft 215. Spring 216 is coupled at a first end to the rod 213 and at a second end to the interior surface of the stairway section side rail. The spring 216 bias the locking pin 127 outwardly so that it engages the aperture in the slide block 122 when the linkage 113 has rotated to a position parallel to the axis of the stairway section side rail (i.e., when the first and second stairway sections have moved to the aligned orientation). Release cable 219 is guided by rollers 220 and 221, and is coupled to rod 213. After the locking pin 127 has engaged the aperture of slide block 122, the locking pin 127 can be withdrawn by momentarily pulling on release cable 219.
FIGS. 11A-11C illustrate an embodiment of the stairway section 111 showing a pivot mount block 150 having a post 152 that engages the slider rail 116 (discussed above with respect to FIGS. 1 and 2). The pivot mount block 150 protrudes outwardly of the body of the stairway section 111 and carries a mount that secures shaft 164 of guide pulley 163. It should be appreciated that using a separate pivot mount block 150 facilitates the construction of the stairway section 111 using conventional extrusion techniques. Alternatively, a unitary construction that includes the stairway section 111 and pivot mount block 150 could also be advantageously utilized.
FIG. 12 shows the interior construction of an embodiment of the first stairway section 111 as taken through a top sectional view. As discussed above with respect to FIG. 7, the cable 19 passes pulley 120 and is guided into the interior of the side rail of the first stairway section 111 by guide pulleys 163, 165 to a termination point 168 at the back of clevis 167. The engagement between post 152 and slider rail 116 is also shown. Clevis 167 carries pulleys 160, 161, which are aligned axially on shaft 162. The first stairway section 111 further includes pulley 175 carried by shaft 176 and pulley 177 carried by shaft 179, each mounted to the interior of first stairway section 111 side rail. Cable 109 originates at shaft 176, then passes around pulley 160, then back around pulley 177, then to pulley 161, then to pulley 175. Thereafter, the cable 109 exits through an opening in the body of the first stairway section 111 as discussed above.
FIG. 13 shows the interior construction of an embodiment of the second stairway section 121 side rail as taken through a top sectional view. After cable 109 enters the opening in the second stairway section 121, the cable 109 is guided into the interior of the stairway section 121 by guide pulley 186 to a termination point 193 at the back of clevis 192. Pulley 187 carried by clevis 192 controls the slack of third cable 209 that enables the deployment of the third stairway section 131. Shaft 195 is movable in slot 197. The shaft 210 is fixed to the interior of second stairway section 121. Cable 209 originates at movable shaft 195, then passes around pulley 187, then back around pulley 188, then to pulley 189. Thereafter, the cable 209 exits through an opening in the body of the second stairway section 121 and enters a corresponding opening of third stairway section 131. Thus, as the payout of cable 109 is increased, pulley 187 moves closer to pulley 188, thereby increasing the payout of cable 209 exiting from second stairway section 121. The movable shaft 195 is further coupled to cable 182 that controls a release of a locking mechanism that couples the first and second stairway sections 111, 121 together.
Referring now to FIG. 14, an alternative embodiment of the first stairway section 111 is shown through a side sectional view. As discussed above, the cable 19 passes pulley 120 and is guided into the interior of first stairway section 111 by guide pulley 163 to a termination point at the back of clevis 167. Clevis 167 carries pulley 161, which controls the slack of a second cable 109 that enables the deployment of the second stairway section 121. The first stairway section 111 further includes pulleys 281, 283, and 285. Pulley 281 is carried by shaft 280 that is slidably disposed in axial slot 288. Pulleys 283, 285 are carried by respective shafts 282, 286 that are mounted to the interior of first stairway section 111. Cable 109 originates at movable shaft 280, then passes around pulley 161, then back around pulley 281, then to pulley 283, then to pulley 285. Thereafter, the cable 109 exits through an opening in the body of the first stairway section 111. Thus, as the payout of cable 19 is increased due to operation of the drive mechanism (described above), pulley 161 moves closer to pulley 281, thereby increasing the payout of cable 109 exiting from first stairway section 111.
A separate structure controls release of a locking mechanism that couples the first and second stairway sections 111, 121 together. The release structure includes cable 306 coupled to movable shaft 280, pulleys 307, 308, 309, and lever arm 303. Lever arm 303 is mounted to the interior of first stairway section 111 at pivot point 305. Cable 306 extends from movable shaft 280, around pulley 307, and terminates at an end of lever arm 303. The opposite end of lever arm 303 has cable 316 coupled thereto. Cable 316 is guided successively by pulleys 308, 309 to the locking mechanism (not shown). When tension is applied to cable 19, such as to retract the stairway sections, pulley 281 is caused to move leftward within slot 288. This transfers tension to cable 306, causing the lever arm 303 to pivot counterclockwise, in turn causing the cable 316 to withdraw and disengage the locking mechanism. Following the initial tension applied to pulley 281, the pulley 281 will return to the approximate center of the slot 288 by back tension applied by cable 109.
FIG. 15 shows an alternative embodiment of the second stairway section 121 through a side sectional view. After cable 109 enters the opening in the second stairway section 121, the cable 109 is guided into the interior of the stairway section 121 by guide pulley 292 to a termination point at the back of clevis 288. Pulley 292 rotates on shaft 293, which is fixed to the interior structure of the second stairway section 121. Clevis 288 carries pulley 290 on shaft 291. Pulley 290 controls the payout of a third cable 294 that enables the deployment of the third stairway section 131. The second stairway section 121 further includes pulleys 303, 295, 297 carried by respective shafts 300, 296, 298. Shaft 300 is movable in a slot 301 against a bias provided by tension in the cables. The shafts 296, 298 are fixed to the interior of second stairway section 121. Cable 294 originates at movable shaft 195, then passes around pulley 290, then back around pulley 303, then successively to pulleys 295, 297. Thereafter, the cable 294 exits through an opening in the body of the second stairway section 121 and enters a corresponding opening of third stairway section 131 (not shown in FIG. 15). Thus, as the payout of cable 109 is increased, pulley 290 moves closer to pulley 303, thereby increasing the payout of cable 294 exiting from second stairway section 121. The movable shaft 300 is further coupled to cable 302, that controls a release of a locking mechanism that couples the second and third stairway sections 121, 131 together (as described above).
FIG. 15 also shows an exemplary device for taking up any excess payout in the various deployment cables. Excess payout may be caused by a number of reasons, such as delay between completion of stairway deployment and the termination of the drive motor 11. As shown in FIG. 15, a loop 390 pulls on cable 294. Cable 391 is also fastened to this loop 390 and is guided by roller 392 that is constrained by pin 393 to spring 394. Spring 394 is selected to have a very small spring constant but with significant stroke so that it can easily take up any excess payout in cable 294 without otherwise interfering with deployment or stowage of the stairway. A similar arrangement may be utilized to take up excess slack in the other stairway sections.
An alternative locking mechanism is illustrated in FIGS. 16A-16B. The exemplary locking mechanism would be formed in an end cap 310 of the first and second stairway sections 111, 121. A cylinder housing 314 is provided within the end cap 310 and includes a corresponding plunger 312 that is axially movable within the cylinder housing 314. The plunger 312 has an axially coupled bolt 311 aligned with an opening 317 provided at an end of the end cap 310. FIG. 16C illustrates the end cap 310 from an end view, showing the opening 317. FIG. 16D shows the plunger 312 and bolt 311 in a perspective view. The opening 317 is substantially aligned with a corresponding receptacle of the second or third stairway sections 111, 121 (discussed below with respect to FIG. 17). The bolt 311 may include a generally rounded end to facilitate engagement with the receptacle. Returning to FIGS. 16A-16B, spring 315 is provided in the cylinder housing 314 and is oriented to bias the plunger 312 so that the bolt 311 extends outwardly of the opening 317, thereby locking the stairway section to the next adjacent stairway section. The plunger 312 is further coupled to release cable 316 (see FIG. 14) (or the other release cables discussed above). By withdrawing cable 316, the plunger 312 and bolt 311 are moved against the bias of spring 315 to thereby withdraw the bolt 311 into the opening 317, and unlock the two stairway sections. Although the plunger 312 is shown as having a round shape, it should be appreciated that other shapes could be utilized, such as a rectangular shape that would eliminate the bulge in the extrusion that forms the stairway sections.
FIG. 17 illustrates a mating end cap 320 adapted to engage the corresponding end cap of FIGS. 16A-16D. The end cap 320 includes a receptacle 322 oriented with respect to the opening 317 to receive the bolt 311 when it extends outwardly of the opening 317. The end cap 320 may further include an insert sleeve 321 adapted to insert into the extruded length of the second or third stairway section 121, 131, and may further include notch 323 corresponding to the axial slot that carries the slide block 112. The end cap 320 may further include one or more mounting holes 324 to carry pulley shafts (as discussed above).
As discussed above, the second and third stairway sections 121, 131 connect together to form a contiguous rail before the entire stairway assembly pivots the final portion before coming to rest on the floor. This portion of the stairway deployment is controlled by a slider release mechanism shown in FIGS. 18A-18C. The slider rail 116 moves up and down relative to a slider release mechanism, and more particularly, the sliding motion relates to the relative distance between the top surface of slider 339 and the lower surface of stop 330. Pivot joints 117 are pivotally mounted to slider 339 and fixedly coupled to the frame 10. The stop 330 located at the end of the slider rail 116 defines the end of travel of the slider rail 116 relative to both the top of the slider 339 and the pivot joint 117, at which point the door 15 and the stairway assembly is fully deployed. The slider rail 116 further includes a partial stop defined by a change in width of the slider rail a short distance from the stop 330. The partial stop provides a pause in the deployment of the stairway assembly to permit the second and third stairway sections 121, 131 to connect together to form a contiguous rail before pivoting the final distance to the floor.
More particularly, a slider 339 carries the pivot joint 117 and is adapted to travel along the length of the slider rail 116. The slider includes a plunger 331 biased into a retracted position by spring 332. The plunger 331 includes a pin 335 that travels within a slot 336, which defines a range of travel of the plunger 331. Release cable 334 controls the movement of plunger 331 against the spring bias. The release cable 334 is guided by roller 337, passes through an opening in pivot joint 117, and terminates at pin 335 of plunger 331. During stairway deployment, the tension in release cable 334 pulls the plunger 331 against the spring bias into engagement with the partial stop of the slider rail 116. This precludes stop 330 on the slider rail 116 from dropping thus preventing the stop 330 from being in contact with the top surface of slider 339 and thus full deployment of the stairway. After the second and third stairway sections 121, 131 have coupled together to form a contiguous rail, the tension in release cable 334 drops so that it cannot overcome the spring bias, thereby retracting the plunger 331 to permit the full extension of the slider rail 116 until stop 330 comes into contact with the top of slider 339.
Referring now to FIGS. 19-21, an exemplary embodiment of a door release mechanism is illustrated. As shown in FIG. 19, the stairway sections 111, 121 are nested in a stowed configuration with the door 15 closed. The door release mechanism includes a, door release plunger having a head 70 and shaft 71. The head 70 is aligned with a corresponding receptacle 85 that is fixed to the door 15. The door release plunger is pivotally arranged relative to pivot point 72 such that, at a first end of travel, the head 70 engages the receptacle 85 (shown in phantom) to thereby lock the door 15. Spring 73 is coupled to the shaft 71 of door release plunger in order to bias the head into engagement with the receptacle 85. A damper 74 is further coupled to the door release plunger via shaft 75 in order to slow the return movement of the plunger following disengagement from the receptacle 85 to permit time for the door to open after actuation of the plunger.
The door release plunger can be activated either automatically or manually. The automatic activation includes release tether 83 that is coupled to an end of the plunger shaft 71. The release tether 83 is guided by rollers 79, 81. Tension applied to the release tether 83 causes the plunger to pivot on pivot point 72 to cause the head 70 to release from the engagement with the receptacle 85. Thereafter, the head 70 will return to the original position by operation of the spring 73 and damper 74. The receptacle 85 includes a rounded top surface that guides the head 70 to engagement with the receptacle when the door 15 is closed. Manual activation of the plunger is provided by release lever 86 that is coupled to plunger head 70 and extends through opening 87 in door 15. Manual movement of the exposed end of release lever 86 causes the plunger head 70 to disengage from the receptacle 85.
Referring briefly to FIG. 23, an exemplary cable release mechanism is illustrated for use with both the slider release mechanism of FIGS. 18A-18C and the door release mechanism of FIGS. 19-21. As discussed above, cable 19 (and 18, not shown) controls the deployment of the stairway sections. Cable 19 passes through a pulley 358 having a movable shaft 359 that travels within a slot 360 in bracket 357. To begin the deployment cycle, the door release mechanism is actuated by operating the drive motor 11 in the stow (reverse) direction. This causes the cables 19 (and 18) to lift pulley 358 and shaft 359 within the slot 360. The movable shaft 359 retracts cable 83 that triggers the door release mechanism to release the door 15. Once the door has released, the direction of motor 11 is reversed, such as activation by a suitable controller or more simply by a micro-switch engaged with the door 15. This allows the cable 19 (and cable 18) to begin to pay out.
While the three stairway sections are deploying, tension in cable 19 remains high while nevertheless still being much lower than that required to release the door 15. This deployment action also keeps cable 83 retracted. Cable 83 branches off to spring 380 at one end and cable 334 coupled to the far end of the spring. During deployment, the tension in cable 19 exerts force on spring 380 and cable 334, and ultimately overcomes the spring bias applied by spring 332 to prevent full deployment of the slider rail 116. As discussed earlier, when all three stairway sections are fully aligned and locked, the tension in cable 19 and spring 380 and cable 334 in direct communication is reduced to a level that is lower than the bias of the spring 332, thus allowing full extension of slider rail 116 to complete the deployment of the stairway. The purpose of spring 380 is to allow cable 83 to fully retract upon the initial deployment sequence (and following the plunger 331 being fully extended against the slider rail 116), thus allowing the door release mechanism to function properly. Accordingly, the spring constant (force) of spring 380 is selected to be much higher than that of spring 332 so not to disrupt the normal function of spring 332 that is intended to operate with lower cable forces.
FIG. 18C shows the slider 339 in cross-section in relation to the mounting frame 10. As discussed above with respect to FIGS. 1 and 2, the pivot joints 117 are supported by bracket 341 and are also pivotally mounted to the slider 339. In addition, the pivot joints 117 also carries deployment pulley 119 used to guide cable 19. Accordingly, deployment pulley 119 moves along slider rail 116 in cooperation with slider 339.
An alternative stairway deployment mechanism is shown in FIGS. 20A-20C. Unlike the preceding embodiment, the motor drive mechanism used to vary the deployment cable tension is contained entirely within individual ones of the stairway sections. FIG. 20B shows a side cross-section of the three stairway sections 111, 121, 131 side rails in the fully stowed or stacked configuration. Stairway section 121 side rail includes a roller 355 that rotates on axle 356, which is oriented to engage an upper surface of stairway section 111 to enable stairway section 121 to move in an axial direction relative to stairway section 111 (see also FIG. 20A). The stairway sections otherwise deploy and retract in the same manner as described above.
Stairway section 121 is further shown as including motor 230 and drive screw 231. The motor 230 is mounted to the interior of stairway section 121 and rotationally drives the drive screw 231. The opposite end of drive screw 231 turns within mount 232. A pulley adjust nut 233 is threadingly engaged with the drive screw 231 such that the pulley adjust nut moves axially along the length of the drive screw 231 as the drive screw rotates. Pulley adjust nut bracket 234 is carried by the pulley adjust nut 233, and in turn carries upper pulley 238 and lower pulley 245. Upper pulley 238 controls the paying out of cable 242 that enables the deployment of the third stairway section 131. Pulleys 236, 237 are fixedly mounted within the stairway section 121 and share a common axle 241. Cable 242 originates at the pulley adjust nut bracket 234, extends around pulley 236, back to upper pulley 238, then back around pulley 237, after which the cable 242 exits the stairway section 121 and engages stairway section 131. With the pulley adjust nut bracket 234 disposed relatively close to the motor 230, the slack in the cable 242 is taken up by the paths between the pulleys 236, 237 and pulley 238. Operation of the motor 230 causes the pulley adjust nut bracket 234 to move and thereby take up the slack in the cable 242. Thus, the drive mechanism produces an extension of cable 242 by a distance that is a multiple of the corresponding movement of the pulley adjust nut bracket 234. It should be appreciated that the first stairway section 111 would have a similar deployment mechanism to facilitate relative deployment of the second stairway section 121.
The lower pulley 245 serves to drive a corresponding mechanism located in the opposite side rail of the stairway section 121. More specifically, the opposite side rail includes a similar mechanism with a drive screw and pulley adjust nut bracket carrying an upper and lower pulley, though it does not include a motor. Instead, the lower pulley 245 shown in FIG. 20B cooperates with pulleys 243, 248 to pay out a driving cable 247 that extends across the stairway to the other side rail, where it drives a corresponding arrangement of pulleys. In particular, driving cable 247 originates at the pulley adjust nut bracket 234, extends to pulley 243, then back around lower pulley 245, then back to pulley 248 then across to crossover pulley 239. The driving cable 247 then exits the stairway section 121 and crosses over to the other side rail of the stairway. Then, the driving cable 247 enters into that opposite side stairway section rail and engages a similar set of pulleys. Thus, as motor 230 causes the slack in driving cable 247 to be drawn in, i.e., when the third stairway section is being drawn in for stowage, the tension in driving cable 247 will cause the pulley adjust nut bracket in the opposite rail to move in a cooperative manner. Accordingly, there is no need for a motor in the opposite side rail of the stairway section.
An alternative embodiment of the slide block used to join adjacent stairway section rails is shown in FIGS. 21A-21C. A slide block plate 350 carries a plurality of rollers 351 that rotate on respective axles 352. The rollers 351 are located adjacent the peripheral corner regions of the slide block plate 350 such that an outer portion of each roller extends beyond the periphery of the slide block plate. Linkage pivot pins 128 extend perpendicularly from the surface of the slide block plate 35 to enable engagement with linkages (not shown) that couple to an adjacent stairway section rail (as discussed above with respect to FIG. 5). The slide block plate 350 is adapted to travel axially within a slot formed in the side of the stairway section rail, such as stairway section rail 121 shown in FIG. 21C. The rollers 351 engage the top and bottom edges of the slot to provide a low friction engagement for movement of the slide block relative to the stairway section rail. Contact surfaces 353 provide additional structural support when the rollers 351 are overloaded, such as when the stairway is in use after being fully deployed.
FIGS. 22A-22C illustrate an exemplary handrail for the stairway sections. The handrail includes an upper handrail 260 and a lower handrail 261 mounted to the first stairway section 111. The upper and lower handrails 260, 261 each comprise a generally S-shaped cross section having a mounting portion that couples to the underside of the first stairway section 111 and a gripping portion that provides a surface adapted to be grasped by a user while climbing the deployed stairway. A space between the upper and lower handrails 260, 261 enables movement of the slider rail 116 discussed above. FIG. 22B shows the handrail and stairway sections in a stowed configuration, and FIG. 22C shows the handrail and stairway sections in a partially deployed configuration. Note that slider rail 116 is not shown in this figure for simplicity. It should be appreciated that a similar handrail may be disposed on the other side of the stairway sections.
Lastly, FIG. 24 illustrates an adjustable foot 364 adapted to engage an end of the third stairway section 131. The adjustable foot 364 enables the length of the deployed stairway sections to be adjusted to accommodate the particular floor to ceiling height of the room in which the stairway is deployed. The foot 364 is coupled to an insert 365 that extends into the end of the third stairway section 131. The insert 365 may include a plurality of adjustment holes aligned with a screw 368 that engages the third stairway section 131 and a selected one of the adjustment holes. The foot 364 may further be provided with a high friction end surface to reduce slippage of the bottom of the third stairway section 131 relative to the floor.
It should be appreciated by those skilled in the art that micro-switches or other like devices that can sense position could be placed in key positions on the stairway to aid in the deployment sequence. More specifically, one or more micro-switches may be positioned to close when the hinge 14 is in the horizontal position and thus the ladder is stowed. Yet another micro-switch could be positioned to close when hinge 14 is in the maximum rotated position, such that it is fully deployed approximately 27° from the vertical. Other micro-switches may be positioned in locations that allow detection that bolts 311 are in the locked position indicating that the first-to-second stairway sections and second-to-third stairway sections are fully deployed and locked together. Additional micro-switches or sensors may be located to sense the door release mechanism position, such as via the position of cable 83 and under the foot of the ladder 364. The above micro-switches and/or sensors could be coupled to a central control unit that receives user input to activate the drive motor 11. Alternately, the micro-switches may provide position feedback that provides an input used to trigger audible or visual alarms, including lights or colored LEDs, such as to indicate deployment status of the stairway. It is further anticipated that the micro-switches or sensors could be positioned at the appropriate locations on both sides of the stairway. It is further anticipated that a mechanical linkage from the lower stairway sections may trigger a micro-switch on the first stairway section 111, such as using a protruding pin that is in communication with the bolt 311 positioned in the corresponding lower section of the stairway. This approach would be advantageous by eliminating (a) the potential for binding of electrical wires across the stairway sections, (b) the need for independent power sources for each stairway section, and/or (c) corrosion of electrical connectors that provide electrical connectivity between the stairway sections.
Having thus described a preferred embodiment of a telescoping attic stairway, it should be apparent to those skilled in the art that certain advantages have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is defined solely by the following claims.

Claims

1. A stairway for use in an opening formed between an attic and a floor below, comprising:

a frame adapted to fixedly engage the opening;

a plurality of stairway sections operatively coupled to the frame and each having a pair of rails and a plurality of steps coupled between the respective rails, the rails further comprising respective upper and lower edge surfaces having corresponding shapes to permit nesting engagement of the stairway sections on top of each other and relative parallel movement of the stairway sections with respect to each other;

wherein, successive ones of the stairway sections are operatively coupled to each other such that they remain nested while being moved relative to each other, and upon reaching an extent of travel relative to each other, orientation of the successive ones of the stairway sections changes to a substantially contiguous and axially aligned structure in which the successive stairway sections are linked end-to-end to provide a continuous stairway.

2. The stairway of claim 1, wherein the rails of at least one of the stairway sections further include a slot extending substantially an entire length of each associated one of the rails.

3. The stairway of claim 2, further comprising a slide block adapted to travel within the slot of a corresponding one of the rails, and a pair of parallel linkages coupled between the slide block and a corresponding one of the rails of a successive one of the stairway sections, the parallel linkages being oriented in a first direction when the successive stairway sections are nested relative to each other and in a second, substantially perpendicular, direction when the successive stairway sections are joined.

4. The stairway of claim 3, wherein the pair of parallel linkages are vertically offset with respect to each other.

5. The stairway of claim 3, further comprising at least one locking pin adapted to lock at least one of the parallel linkages in the second direction.

6. The stairway of claim 3, wherein the slide block further comprises at least one roller adapted to engage the slot to facilitate low friction movement of the slide block within the slot.

7. The stairway of claim 1, further comprising a door hingedly attached to the frame, at least a first one of the stairway sections being fixedly coupled to the door.

8. The stairway of claim 7, further comprising a locking finger operatively coupled to the frame and oriented to engage a corresponding opening of the door to thereby lock the door in a closed position when the stairway sections are stowed.

9. The stairway of claim 8, further comprising a manual release lever adapted to disengage the locking finger from the opening.

10. The stairway of claim 8, further comprising a release cable adapted to disengage the locking finger from the opening upon deployment of the stairway sections.

11. The stairway of claim 7, further comprising a pivot joint coupling the rails of the first one of the stairway sections to the door, the pivot joint permitting the rails of the stairway sections to be folded parallel to the door to provide a compact profile.

12. The stairway of claim 1, wherein the steps are selectively detachable from the rails.

13. The stairway of claim 1, further comprising at least one slider rail coupled to the first one of the stairway sections, the frame further comprising a pivot point that slidably engages the at least one slider rail, wherein the slider rail defines a range of motion of the plurality of stairway sections in pivoting from a substantially horizontal stowed orientation to a deployed orientation disposed at a predetermined angle from horizontal.

14. The stairway of claim 13, wherein the at least one slider rail further comprises an end stop defining a limit of travel of the slider rail with respect to the pivot point.

15. The stairway of claim 14, wherein the at least one slider rail further comprises a temporary stop prior to the end stop defining an initial angle for deployment of the stairway sections prior to coming into contact with the floor.

16. The stairway of claim 1, further comprising at least one deployment cable associated with each rail of the plurality of stairway sections, the at least one deployment cable controlling relative movement of the plurality of stairway sections such that relative movement in a stairway deployment direction is provided by paying out the at least one deployment cable and relative movement in a stairway stowing direction is provided by retracting the at least one deployment cable.

17. The stairway of claim 16, further comprising a rotatable drive screw carrying at least one pulley engaged with the at least one deployment cable, wherein rotation of the drive screw in a first direction provides paying out of the at least one deployment cable and rotation of the drive screw in a second direction provides retraction of the at least one deployment cable.

18. The stairway of claim 17, further comprising an electric motor operatively coupled to the drive screw to enable powered rotation of the drive screw in selected ones of the first and second directions.

19. The stairway of claim 18, wherein the electric motor and the drive screw are coupled to the frame.

20. The stairway of claim 18, wherein the electric motor and the drive screw are disposed within at least one of the plurality of stairway sections.

21. The stairway of claim 17, further comprising a removable crank adapted to be operatively coupled to the drive screw to enable manual rotation of the drive screw in selected ones of the first and second directions.

22. The stairway of claim 17, further comprising a pull rope operatively coupled to the drive screw to enable manual rotation of the drive screw in selected ones of the first and second directions.

23. The stairway of claim 22, wherein the pull rope is adapted to retract when not in use.

24. The stairway of claim 23, further comprising a removable hook adapted to retrieve the pull rope when retracted.

25. The stairway of claim 17, further comprising a control circuit adapted to control operation of the electric motor.

26. The stairway of claim 25, wherein the control circuit includes at least one micro-switch adapted to sense a deployment condition of at least one of the stairway sections.

27. The stairway of claim 1, wherein the plurality of stairway sections further comprises at least three stairway sections.

28. The stairway of claim 1, wherein the plurality of stairway sections further comprises at least two stairway sections.

29. The stairway of claim 1, further comprising at least one locking pin adapted to lock the successive stairway sections in an end-to-end configuration.

30. The stairway of claim 1, wherein the upper edge surfaces of the plurality of stairway sections further comprises a generally convex rounded shape, and the lower edge surfaces of the plurality of stairway sections further comprises a generally concave rounded shaped adapted to nest with the generally convex rounded shape of the upper edge surfaces.

31. The stairway of claim 1, wherein the lower edge surfaces of at least one of the plurality of stairway sections further comprises at least one roller adapted to enable low friction sliding engagement between successive ones of the stairway sections.

32. The stairway of claim 1, further comprising at least one handrail coupled to at least one of the plurality of stairway sections.

33. The stairway of claim 1, wherein one of the plurality of stairway sections adapted to come into contact with the floor further comprises an adjustable foot.