Abstract:
A collapseable spider wheel assembly on a towing device enables storage of the device into a standard rectangular space. Once collapsed, the collapsible spider assembly is protected within the body of the towing device. Furthermore, actuation of the folding and unfolding may be accomplished through the usual telescoping of the carrying handle of such a device, such as in a suitcase embodiment. While the spider wheels are in the open position, the carrying apparatus may exert a drive force to climb up stairs and braking force to descend stairs. The unit operates as a normal wheeled carrying apparatus while traversing a horizontal surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to devices for ascending stairwells that employ a “cluster,” “X,” “Y,” “spider,” or “wheel-over-wheel” assembly. 
         [0003]    2. Description of the Related Art 
         [0004]    Towing items such as suitcases and luggage have limited facilities when traversing stairwells. While ascending/descending stairwells, the owner of the towing device has to lift it up and over the corner of each step rendering the wheels useless in this situation. This also leads to a jerking motion as the towing device hops from stair to stair. 
         [0005]    Conventional luggage has shown the inclusion of skids on the back of the suitcase panel to ease the suitcase sliding up the stairs. However, these skids typically wear down with use, and not as frictionless as they need to be. Conveyor belts have been proposed: U.S Published Application No. 20040094378 describes a motorized suitcase with brake that utilizes tank treads and rollers. Conveyor belts generally lack adequate grip on stairwells for personal suitcases since the unit may only be in contact with the leading edges of 2-3 stairs at most. Such units must lay flat along the stairs and be heavy enough to create a downward force for the tank treads to effectively grip the stairs and require an overly-lengthy handle for proper use. 
         [0006]    Other devices that employ “spider wheels,” “cluster wheels,” or “wheel over wheel,” mechanisms for stair climbing are known. Such devices utilize small, freely-rotating wheels fastened at the ends of spokes that rotate all together as a rigid assembly. PCT Patent Publication No. WO8600587A1 describes a stair-climbing hand truck utilizing rotating spider wheels. Spider wheel assemblies, however, protrude from the main body of a towing device, reducing overall portability. 
         [0007]    U.S. Pat. No. 6,484,829, a battery powered stair-climbing wheelchair utilizing two sets of wheel-over-wheel assemblies is described. In that particular vehicle, however, the design addresses mechanisms that controls pitch and attitude adjustment for complete support, orientation, and self-propulsion of human beings up and down stairwells. The preferred embodiment of that vehicle does not include any means of rendering the cluster wheel foldable or collapsible for portability. 
         [0008]    This invention introduces a collapsible spider wheel assembly, rendering the towing device to which it is attached, portable for transport. Such towing devices may include but is not limited to: suitcases, hand trucks, and baby strollers. 
       SUMMARY OF THE INVENTION 
       [0009]    Briefly described, the invention comprises a collapsible spider assembly that is coupled to an end of a driveshaft of a towing device. The collapsible spider assemblies are folded in and out by the user pushing/pulling the telescoping handle via a lever system. The central driveshaft may rotate freely, even when the spider assembly remains locked in its open position. In the locked open position, the spider wheel may operate in a conventional manner, facilitating ascent and descent of stairwells. The invention may be more fully understood by reference to the following drawings. 
         [0010]    The invention will be more fully described by reference to the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an isometric view of a suitcase employing the collapsible spider assembly. 
           [0012]      FIG. 2  is an isometric view of the suitcase apparatus being configured for level travel with item # 72 , protective shell, hidden from view. 
           [0013]      FIG. 3  is an isometric view of the foldable spider wheel apparatus being configured for an open position. 
           [0014]      FIG. 4  is an isometric zoomed-in view of the foldable spider wheel apparatus as illustrated in  FIG. 3  with parts  38 B- 38 F removed for greater visibility. 
           [0015]      FIG. 5  is an isometric assembly view of the foldable spider wheel apparatus as illustrated in  FIG. 3  and  FIG. 4 . 
           [0016]      FIG. 6  is an isometric zoomed-in assembly view of the foldable spider wheel apparatus as illustrated in  FIG. 3 ,  FIG. 4 , and  FIG. 5 . 
           [0017]      FIG. 7  is an isometric exploded view of rotational coupler,  38 A- 38 F, as illustrated in  FIG. 3 . 
           [0018]      FIG. 8  is an isometric view of the foldable spider wheel apparatus being configured for a closed position, configured for portability. 
           [0019]      FIG. 9  is an underside isometric view of the foldable spider wheel apparatus being configured for a closed position, configured for portability, as illustrated in  FIG. 8 . 
           [0020]      FIG. 10  is a side elevation view of the spider assembly being configured for a folded position. 
           [0021]      FIG. 11  is a side elevation view of the spider assembly being configured for an open position. 
           [0022]      FIG. 12  is a table of geometrical calculations of the lengths listed in  FIG. 10  and  FIG. 11 . 
           [0023]      FIG. 13  is a front elevation view of the telescoping handle folding mechanism being configured for an open position, configured for travel. 
           [0024]      FIG. 14  is an isometric view of the telescoping handle folding mechanism being configured for an open position, configured for travel. 
           [0025]      FIG. 15  is a zoomed-in front elevation view of the telescoping handle folding mechanism being configured for an open position, configured for travel as illustrated by  FIG. 14  and  FIG. 13 . 
           [0026]      FIG. 16  is an isometric view of the telescoping handle folding mechanism being configured for an open position with protective shell being shown. 
           [0027]      FIG. 17  is a front elevation view of the telescoping handle folding mechanism being configured for a closed position, configured for portability. 
           [0028]      FIG. 18  is an isometric view of the telescoping handle folding mechanism being configured for a closed position, configured for portability as illustrated by  FIG. 17 . 
           [0029]      FIG. 19  is a zoomed-in front elevation view of the telescoping handle folding mechanism being configured for a closed position, configured for portability as illustrated by  FIG. 17  and  FIG. 18 . 
           [0030]      FIG. 20  is an isometric view of the telescoping handle folding assembly being configured for a closed position, with protective shell being shown. 
           [0031]      FIG. 21  is a front elevation illustration of an alternative embodiment for the spider folding assembly in the open position. 
           [0032]      FIG. 22  is a front elevation illustration of an alternative embodiment for the spider folding assembly in the folded position. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
         [0034]    Referring initially to  FIG. 1  and  FIG. 2 , the preferred embodiment comprises protective shell  72  that encloses foldable spider wheel apparatus  29  leaving only wheels  30 B and  30 C exposed to roll freely along flat ground. Thus,  30 - 38  fold into protective shell  72 , rendering foldable spider wheel apparatus  29  durable and portable, ideal for storage in a trunk or overhead luggage compartment.  FIG. 2  reveals a view of foldable spider wheel apparatus  29  without protective shell  72  allowing for greater visibility.  30 - 38  are fastened to central shaft  40  that runs through body square angles  52 A and  52 B. Handle  58  telescopes up and down, sliding within square angle  52 , and activates the folding mechanism via T-shaped motion translator  48  and rigid connecting arms  50 .  30 - 38 , central shaft  40 , square angle  52 , and handle  58  comprise the elements that give the main structural rigidity to foldable spider wheel apparatus  29 . 
         [0035]    The foldable spider apparatus is pictured in  FIG. 3  through  FIG. 6 . Three small wheels  30 A-C are fastened to the ends of legs  34 A and  34 B such that the wheels may freely rotate. Legs  34 A and  34 B are fastened with connecting arms  36  with back plate  32 . Legs  34 A and  34 B are hinged to arm back plate  32  such that the hinges would meet at a right angle if extended, and that arm with back plate  32 , leg  34 A and leg  34 B meet at 120° when laid in a single plane. Accordingly, leg  34 A and leg  34 B may rotate along their hinges to fold perpendicular to arm with back plate  32 . Assembly is pictured in  FIG. 5  and  FIG. 6 . Connecting arms  36  are hinged at one end to leg  34 A, respectively, and to rotational rotary anchor  38 A on the other end, such that the hinges lie parallel with each other. The assembly is rigidly fastened to central shaft  40 . 
         [0036]    The rotational coupler,  38 A- 38 F is illustrated in  FIG. 7 . Fasteners  38 B rigidly fasten rotational rotary anchor  38 A to end piece  38 C. Likewise fasteners  38 E rigidly fasten rotational coupler  38 D to coupler end piece  38 F.  38 D- 38 F, as assembled, fits around  38 A- 38 C, such that  38 D- 38 F may rotate freely, even when an axial thrust force is applied to  38 A- 38 C. Such a thrust force causes the spider wheel to unfold. In this situation, any force directed radially inward on legs  34 A or  34 B to fold in is redirected through connecting arm  36  and exerts a thrust force on  38 A- 38 C, radially inward on central shaft  40 . Despite large forces directed on legs  34 A and  34 B, to fold in, the unit remains locked in the unfolded position due to the geometry of leg  34 A, leg  34 B and connecting arms  36 A and  36 B lying flush against one another in a single plane. Thus formed, rotary coupler  38 D- 38 F remains freely rotating around anchor  38 A- 38 C, so that the spider wheel apparatus may rotate around central shaft  40  without rotating rigid connecting arms  50  that keep the spider apparatus unfolded remaining fastened to the body  52 . 
         [0037]    Accordingly, the spider apparatus ( 30 - 38 ), once unfolded, is equivalent to a standard rigid spider wheel assembly with a set of three spokes with three small freely-rotating wheels on each end that is effective for both flat surfaces and for climbing stairs by rotating around central shaft  40 . The legs may fold in, as pictured in  FIG. 8  and  FIG. 9 . As legs  34 A and  34 B rotate perpendicularly to arm with back plate  32  along a hinge, connecting arms  36 A and  36 B also rotates along its hinges, and  38 A- 38 F slides along central shaft  40 . Thus, the folding/unfolding motion is similar to that of a folding umbrella. The design of the spider assembly as mentioned requires minimal force exerted by the user to actuate folding and unfolding. 
         [0038]    Alternative embodiments of an umbrella-like folding mechanism can also extend and retract the spider wheels. However, the geometry of the preferred embodiment is such that the spider assembly locks in position with a small user-applied force, does not collapse under large forces on the wheels, and unlocks and folds with minimal user-applied force. The distinguishing characteristic of this geometry lies in the fact that connecting arms  36 A and  36 B lies parallel with legs  34 A and  34 B in the open position, and thus, any external force on radial coupler  38 A- 38 F is directed radially inward on central shaft  40 , preventing accidental folding of the assembly. This radial force can easily be opposed by central shaft  40  only if connecting arms  36 A and  36 B and legs  34 A and  34 B lie parallel in the closed position. Thus, external forces will not push the wheels out of their locked state. The geometry of the assembly is depicted in  FIG. 10 ,  FIG. 11 , and  FIG. 12 . 
         [0039]    In addition, varying the length of connecting arms  36 A and  36 B and the location of holes on legs  34 A and  34 B and on rotary anchor  38 A, the geometry of the folding mechanism can be adjusted. By changing the lengths and positions of connecting arms  36 A and  36 B and the hinges on legs  34 A and  34 B, the angle between the connecting arms  36 A and  36 B and legs  34 A and  34 B can be varied, in order to reduce the necessary force required to open the spider from the closed position. If the angle theta is too shallow, an axial force to push rotary coupler  38 A- 38 F along central shaft  40  becomes too large to open the assembly. Thus, a near-optimal set of distances to achieve a large enough angle theta and adequate travel for  38 A- 38 F along central shaft  40  is set in bold in  FIG. 12 . The column labeled ‘suboptimal gap’ computed in  FIG. 12  is the difference of theta and 45°. Theta equaling 45° provides connecting arms  36 A and  36 B with the optimal mechanical advantage to open legs  34 A and  34 B from closed position, so the preferred embodiment minimizes the suboptimal gap as well as rendering the travel distance for radial coupler  38 A- 38 F within the design constraints so that  38 A- 38 F does not collide with body angle  52 . 
       Activation of Folding and Unfolding 
       [0040]    The folding motion of the aforementioned spider assembly is activated by the user via telescoping the carrying handle  58  in the case of storing foldable spider wheel apparatus  29  for portable transport. Telescoping handle  58  additionally folds in the spider assembly. Referring to  FIG. 13  through  FIG. 16  illustrate various views of the suitcase with spider wheels completely unfolded, i.e. extended and ready to traverse terrain. Rotary couplers  38 A- 38 F on the aforementioned spider assembly are hinged to rigid connecting arms  50  that are in turn fastened to T-shaped motion translator  48 . T-shaped motion translator  48  is fastened in through its center to motor drive system  49  that is rigidly fastened to square angle  52 . Thus, T-shaped motion translator  48  may freely rotate around its center axis. T-shaped motion translator  48  includes a protruding arm with a vertical sliding channel in it, through which inner sliding angle  54  is fastened. 
         [0041]    To unfold the spider assembly  30 - 38  for use, the user lifts handle  58  vertically. This lifts inner sliding angle  54 , to which handle  58  is fastened, which slides within square angle  52 . Lifting inner sliding angle  54  causes T-shaped motion translator  48  to rotate counter-clockwise, as pictured in  FIG. 15 , which rotates rigid connecting arms  50  outward, pressing on  38 A- 38 F in an outward direction on central shaft  40 . This happens on both the left and right spider wheel assemblies, causing both to unfold into fully extended positions. 
         [0042]    To fold the spider assembly  30 - 38 , for portability, the user presses handle  58  down vertically, activating the reverse process. The folded in position is illustrated in  FIG. 17  through  FIG. 20 . Inner sliding angle  54  then moves downward within square angle  52 , causing T-shaped motion translator  48  to rotate clockwise, as pictured in  FIG. 19 , which rotates rigid connecting arms  50  inward, pulling  38 A- 38 F inward on central shaft  40 , causing both left and right spider wheel assemblies to fold in. Accordingly, protective shell  72  has depressions on its bottom and back sides allowing the arm and wheels,  30  and legs  34 A and  34 B, to fit within the shell and lie flush against the back and bottom, as pictured in  FIG. 16  and  FIG. 20 . 
         [0043]    Thus, a complete fold-in, fold-out-lock mechanism is achieved that is operated by a simple pushing down and pulling up of the telescoping handle  58  on the main body. 
       ADVANTAGES 
       [0044]    Accordingly, it is the object of this invention to enable a towing device&#39;s spider assembly to fold into a protective enclosure enhancing portability and durability overall. In addition, several objects and advantages of this invention are: 
         [0045]    a.) to introduce a collapsible spider wheel apparatus for portability; 
         [0046]    b.) to allow the locking of the spider wheel in open position requiring an asymmetrically low input force from the user; 
         [0047]    c.) to allow for the central driveshaft to rotate while the spider wheel remains in a locked open position; and 
         [0048]    d.) to enable the user to actuate the fold-in, fold-out mechanism through the normal handle telescoping motion of an embodiment such as a suitcase. 
         [0049]    While the invention has been described with reference to the preferred embodiment thereof, it will be appreciated by those of ordinary skill in the art that modifications can be made to the structure and elements of the invention without departing from the spirit and scope of the invention as a whole. 
       ALTERNATIVE EMBODIMENTS 
       [0050]    The third arm of the spider folding apparatus may also fold in a similar manner, along with the other two arms. Thus, arm with back plate  32  could be appropriately hinged as are legs  34 A and legs  34 B such that all three arms fold in when  38 A- 38 F moves inward. 
         [0051]    Another method to collapse the spider apparatus includes rendering each leg  34 A and leg  34 B broken in the middle but freely rotating perpendicular to the direction of that of the preferred embodiment. Thus, each leg  34 A and leg  34 B swivels inwards toward the middle, with assistance from gears that are fastened to each side of leg  34 A and leg  34 B. An illustration is provided in  FIG. 21  and  FIG. 22 . 
         [0052]    Another method of folding the spider apparatus includes screwing each of the three arms of the spider apparatus onto central shaft  40 , which is threaded very coarsely, with a large pitch such that the arms will rotate when pushed axially, but will not move axially when rotated. With a small amount of movement in the axial direction, two of wheels  30 A and  30 B will rotate 120 degrees and 240 degrees, respectively, to stack all of the wheels collinearly for easy storage. The two positions, folded and unfolded, may be controlled by a single motion of a spring-loaded lever that pushes and pulls the spider arms along the driveshaft. 
         [0053]    Yet another method of folding in the spider apparatus is allowing the entire assembly,  30 - 38  with central shaft  40  to lie on a track that may shift into the central protective enclosure. Thus, the wheel fixture may be translated upward so that it does not protrude from the front of the body, protective shell  72 . 
         [0054]    It is to be understood that the above-described embodiments are illustrative of only a few of the many possible specific embodiments, which can represent applications of the principles of the invention. Numerous and varied other arrangements can be readily devised in accordance with these principles by those skilled in the art without departing from the spirit and scope of the invention.