Abstract:
A pull-down shelf for storage of articles has a lower shelf portion that contains a wind-up mechanism, which can be spring powered or motorized, an overhead mounting plate that attaches to ceiling joists or the like, and at least a pair of cables that are wound onto arbors of the wind-up mechanism for suspending the shelf portion from the overhead mounting plate. Scissors-action stabilizers hold the shelf from tipping or swinging. The user pulls the shelf down, and this unwinds the cables and charges the springs. A releasable ratchet wheel keeps the mechanism from turning in the rewind direction. The user can pull or actuate a release handle or button to release the shelf and let the spring rewind the cables to pull the shelf back to its overhead position.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to storage and work shelf devices for out-of-the-way storage of items, and is more particularly concerned with shelf arrangements that permit overhead storage, e.g., in a garage of other structure, which can be raised overhead when not in use and can be lowered for use, i.e., by pulling the shelf down to a lowered, working position. 
   Shelves are often and commonly used for storing items, such as clothing, towels, gardening equipment, tools, cleaning compounds, or other items. However, in order to be useful the shelf has to be low enough to allow access to frequently used items, but high enough to allow the space beneath the shelf to be utilized. In living areas shelves are commonly installed in the top of a closet or above counters, workbenches or desks. In other areas, such as garages and basements, shelves are placed higher on walls, or hung from ceilings to allow better use of the space underneath them. This space is often required for workshop tools, lawn mowers, snow blowers, or other equipment, or simply to allow room to open the garage door. Garage shelves must generally be mounted high enough to allow room to walk underneath, thus requiring a stepladder or step stool for access to items stored on the shelf. Because of the inconvenience of the higher shelf, only less frequently used items are stored there. More frequently used items tend to be placed in floor level cabinets or simply left on the floor, thus taking up the very floor space that the overhead shelf was intended to save. 
   A number of disappearing cabinets and shelves have been proposed in the art. For example, LaVee U.S. Pat. No. 4,669,773 is directed to a storage pod for overhead storage in the roof of a vehicle, and employs lazy tong linkages and counterbalance coil springs. Quackenbrush U.S. Pat. No. 3,829,912 relates to a bed assembly that retracts into an overhead space. Huffman U.S. Pat. No. 5,261,645 concerns a remotely controlled lifting shelf for supporting a video projection machine, and has a motorized cable system to draw the support shelf and video projector up into a recess in the ceiling. McCoy U.S. Pat. No. 5,475,949 is concerned with a closet that is supported overhead in an enclosure that fits into the ceiling joists, in which the closet can be pulled down for use, and retracts by spring action into the enclosure in the ceiling. Thorp U.S. Pat. No. 6,250,728 relates to a similar hanging closet arrangement, but one in which a torsion spring provides the power to wind a cable onto a pulley and pull the closet up into the overhead housing. None of these prior arrangements would be suitable for a storage shelf for a garage or basement, for example, in which the shelf could be simply pulled down to a lowered position for use and could be released to be raised to an overhead storage position. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   Accordingly, it is an object of this invention to provide an overhead storage shelf that can be easily lowered for access to the articles on the shelf, and which avoids the drawbacks of the prior art. 
   It is a more specific object to provide a storage shelf that allows the stored items to be kept at a space just below the ceiling of the garage, basement, or other structure, which is convenient to lower for use, and return easily to the upward or raised storage position. 
   It is another feature to provide a shelf that can be moved vertically, and in which the mechanism for raising or lowering the shelf is situated in the movable shelf rather than in the overhead support. 
   In accordance with an aspect of this invention, a pull-down storage or work shelf arrangement has an overhead mounting plate that attaches either to ceiling joist or to vertical wall studs at an overhead position, and a vertically movable storage shelf. The shelf has an upper platform, and may have a base member beneath it. A spring-loaded wind-up mechanism mounted on it, or within the shelf portion of the assembly. The wind-up mechanism has a pair of arbors that are driven to rotate by a spring. A ratchet wheel or cam on the shaft for the arbors releasably locks the arbors against rotation in a rewind direction. Typically, this involves a pawl mechanism with a lever that is spring biased towards the ratchet wheel and a tooth that engages the ratchet teeth, and a release cord (or button) that is actuated to release the pawl from the ratchet. There are first and second cables wound onto the two arbors, respectively, and these extend upward such that the upper ends of the cables attach to anchor points on the mounting plate. In order to stabilize the shelf against tipping, twisting, or swinging, there are first and second scissors-action stabilizer linkages mounted at the left and right ends of the shelf and also at the left and right ends of overhead mounting plate. 
   When the user needs access to the articles on the shelf, the user pulls down on the shelf to lower it from a raised position thereof to a lowered position. There may be a cord or handle on the bottom or base of the shelf for this purpose. When the shelf descends, the cables unwind from the arbors of the wind-up mechanism and this charges the spring. The ratchet mechanism engages and locks the wind-up mechanism from rotation in the rewind direction, so that the shelf remains in its lowered position. The scissors-action stabilizer linkages stabilize the shelf. When the user if finished with the articles on the shelf, he or she simply actuates the release mechanism on the ratchet mechanism, i.e., by pulling on a release cord or pressing a release button, and the wind-up mechanism rewinds the cables back onto said arbors to lift the shelf to its raised position. 
   By having the motive element, that is the wind-up mechanism, located within the lower shelf rather that in the fixed overhead support element, the user has better positive control over positioning the shelf when it is lowered, and in releasing the shelf to let it ascend to its storage position. 
   In one favorable embodiment, the wind-up mechanism includes a rod or shaft that is journalled to either the base or the platform of the shelf. The arbors can be formed at ends of the rod. The spring can be a torsion spring that is disposed over the rod between the two arbors. 
   An adjustable guard railing can extend around the periphery of shelf platform so that items do not slide or fall off the shelf. 
   In a favorable embodiment, the overhead mounting plate has an L-shaped profile to permit mounting on either of an overhead horizontal support member (such as ceiling joists) or a vertical support member (such as vertical wall studs). 
   The scissors-action stabilizer linkages are formed of a number of elongated slat members that are each joined by low friction pivots at their center to a center of another of the slat members, and are also pivoted at their ends to an end of another of the slat members. 
   Another embodiment of a raiseable and lowerable storage or work shelf arrangement can involve the same structure as in the embodiment just mentioned, except having a motorized wind-up mechanism mounted on the shelf (or within the shelf) and in which the pair of arbors rotate under action of a motor, e.g., an electric gear motor. In this embodiment, the user actuates the motor to lower the shelf from its raised position to a lowered position. The motor rotates the cables in an unwind direction, and the cables unwind from the arbors. A locking mechanism locks the wind-up mechanism against rotation with the shelf in its lowered position. As with the first embodiment, the scissors-action stabilizer linkages stabilize the shelf against tipping, twisting, or swinging. When the user actuates a control for the motor to raise the shelf, a release mechanism releases the wind-up mechanism, and the latter rewinds the cables onto the arbors to lift the shelf to its raised position. 
   The above and many other objects, features, and advantages of this invention will become apparent to persons skilled in the art from the ensuing description of a preferred embodiment, which is to be read in conjunction with the accompanying Drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a schematic perspective view of a pull-down shelf arrangement, according to one possible embodiment of this invention. 
       FIG. 2  is schematic partial perspective of the shelf portion of this embodiment. 
       FIG. 3  is a sectional elevation of the shelf portion of this embodiment. 
       FIG. 4  is an assembly view of the pivot portion of the scissors action stabilizer of this embodiment. 
       FIG. 5  is a schematic elevation for explaining another embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to the Drawing, and initially to  FIG. 1 , a pull-down shelf assembly  10  is provided to allow items to be stored, e.g., just below the ceiling or overhead joists of a garage, basement, or other area, where the space would be otherwise unusable or inaccessible. The shelf arrangement  10  has an overhead mounting plate  12 , which in this embodiment has an angled or L-shaped profile, with a horizontal upper or top plate  14  and a vertical back plate  16 . The top plate and back plate are provided with mounting holes  18 , spaced so as to match the positions of ceiling joists or vertical wall studs. A shelf  20  is suspended below the mounting plate  12 , and in this embodiment is formed of an upper platform  22  and a lower base plate  24 . Here, the shelf is in the form of a box of which the platform and base plate form the top and bottom. A peripheral railing  26  is provided on the platform  22  to retain items that are placed on the shelf. A pair of cables  28  extend from the shelf  20  up to anchor points in the mounting plate  12 , and a spring powered wind-up mechanism  30  within the shelf  20  operates to play out the cable or to rewind it to lower and raise the shelf  20 . This wind-up mechanism will be discussed in detail shortly. 
   Right and left side scissors-action stabilizers  32  are connected to right and left ends, respectively, of the overhead mounting plate  12  and to right and left ends of the shelf  20 . Each of the stabilizers  32  is formed of a number of elongated slats or arms  34 , which are pivotally connected to one another in a criss-cross fashion. There are pivot members  36  joining each of the arms  34  to another arm  34  at ends and at the centers, as shown. The action and construction of these scissors-action stabilizers is well known in this field. The stabilizers ensure that the shelf  20  is kept level, that is, so that is does not tip, swing, or twist, while it is being raised or lowered. 
   The spring-loaded or spring-powered wind-up mechanism  30  is shown in  FIG. 2. A  horizontal rod or shaft  40  has a torsion spring or springs  42  mounted over it, with a spring anchor on the base plate  24 . There are bearings or journals  44  attached to the base plate that permit rotation of the shaft  40 , and pin(s) or bar(s) for holding the outer end(s) of the spring  42  fast to the shaft  40 . The cables  28  are wound onto arbors  50  that are formed at the left and right ends of the shaft  40 , and which may be formed either as a portion of the shaft or as separate members operatively coupled to rotate with the shaft. In operation, the spring force acts to wind the cables  28  onto the arbors  50 , and the withdrawal of the cables  28  turns the shaft  40  in the direction to charge the spring or springs  42 . There are a pair of sleeves  52 , which may be constituted of a low-friction tubular material, or may include a lubricant material, fitted into the shelf platform  22 , and through which the two cables  28  pass. An anti-rotation mechanism  54  on the shaft  40  prevents the wind-up mechanism  30  from rotating the shaft  40  and arbors  50  in the re-wind direction until the user releases a catch or pawl, so the shelf remains in the lowered position until the user affirmatively releases it. 
   As shown in  FIG. 3 , the anti-rotation mechanism  54  can take the form of a toothed ratchet wheel or cam  56  with a pawl or locking lever  58 . The ratchet wheel  56  is mounted coaxially with the shaft  40  and arbors  50 . The arrow indicates the direction of rotation when the shelf is pulled down, i.e., when the cable  28  pays out, to charge the spring  42 . The pawl or locking lever  58  is mounted on a pivot  60  and is biased by a spring  62  into engagement with the teeth on the ratchet wheel  56 . In this embodiment, there is a release cord  66  attached to the lever  58  with a handle  68 . The user can pull the cord  66  and handle  68  to release the anti-rotation mechanism  54  so that the shelf can be returned to its upper, or storage position near the mounting plate  12 . 
   Attached onto the bottom of the base plate  24  are one or more handles  70  which the user may use to pull the shelf  20  down from its overhead position to its lowered position. A rope pull  72  may also be used, for initially lowering the shelf when the shelf is high overhead. 
   The pivot members  36  for the scissors-action stabilizers  32  may incorporate the general structure that is shown in FIG.  4 . Here, for each pivot point between two slats or arms  34  there is a law-friction plastic sleeve  74  which fits into respective pivot openings in the two arms  34 . This sleeve may be made of a synthetic material. e.g. a durable plastic with a lubricant filler. A low-friction washer  76  may be placed at one side, and a suitable fastener  78  is fitted through the sleeve  74  and washer  76 . In this embodiment, the fastener may be constituted by a bolt and nut. 
   When the user wants to access items stored on the shelf  20 , he or she pulls it down, using the rope pull  72  and handle(s)  70 . The lowering of the shelf  20  pays out the cables  28 , and they rotate the shaft as they unwind from the arbors, thus charging the spring  42 . The ratchet mechanism  54  prevents the spring  42  from recoiling, and holds the shelf  20  at the desired height. When the items have been placed on the shelf  20  or retrieved from it, the user can release the ratchet mechanism by pulling on the release cord  66 , allowing the cable to rewind and pull the shelf  20  back up to its overhead storage position. The adjustable railing  26  prevents items from falling off the shelf during raising or lowering. 
   The mounting plate  12  can be made of metal, wood, fiberglass, or a suitable plastic. The shelf  20  can be made of wood, metal, fiberglass or other strong material. In this embodiment, the shelf  20  is of hollow construction, with the wind-up mechanism contained inside it. In other possible embodiments, there may be a cover over the wind-up mechanism, either on top of or beneath the platform. If the preferred box construction is followed, the sides of the shelf between the base and platform portions may be made of a pegboard material or other perforated material, so that tools or other items may be suspended from the sides in pegboard fashion. 
   The retracting cables may be any suitable cable material, preferably a coated flexible material such as steel, aluminum or nylon. The rod or shaft  40  may favorably be about one-inch in diameter, with the spring  42  having a sufficient open core to fit over this rod. The rod or shaft may be of metal or of any suitable material e.g., reinforced fiberglass, that can hold up after repeated use. 
   The shelf assembly of this invention can have a wide variety of applications outside of garage or basement storage. The shelf can be given a finished decor, and used in an office environment, e.g., disappearing into a false or suspended ceiling. The shelf can have file cabinet drawers mounted on it to create additional office filing space. An electric outlet may be added to use small appliances such as a coffee maker or a microwave oven. Additional shelves may be attached to make a multi-tiered configuration. 
   Preferably, the shelf has three handles  70 , and each may have its own rope pull  72  attached. The rope pulls can be adjusted to various heights to prevent smaller children from being able to access the shelf. 
   An alternative embodiment is shown, in pertinent part, in FIG.  5 . Here, the parts that are identical with the first embodiment are identified with the same reference characters, or are omitted from this view. The shelf  20 , the cables  28  and the side scissors-action stabilizers  32  can be of the same general construction as discussed above. However, in place of the spring-action wind-up mechanism of the previous embodiment, this embodiment employs a motorized wind-up mechanism  130  situated in the shelf  20 . The wind-up mechanism  130  is constituted by an electric motor  132 , plus gears and a worm drive coupled to rotate the arbors  134  on which the cables  28  are wound. A hand-actuated power controller  136  is shown here hanging down from the shelf  20  and coupled to the motor by means of a coiled cord  138 . The electric power for the motor maybe provided via a power cord that passes down from the overhead mounting plate to the shelf. In this embodiment, the wind-up mechanism  130  favorably includes a brake or other anti-rotation mechanism provided with a release mechanism, so that the shelf remains stable in its raised and lowered positions. Having the motorized wind-up mechanism  130  and its controls located in the lower shelf portion rather than overhead in the mounting plate provides advantages in operation as was the case in the earlier-described embodiment. 
   Many other modifications and variations are possible which would not depart from the scope and spirit of this invention, as defined in the appended claims.