Abstract:
An improved umbrella includes a durable hub including a number of spherical rotating joint knuckles captured in a hub body. The joint knuckles provide rotational movement of rib and spreader elements which support a flexible umbrella cover. The joint knuckles provide increased bearing surface area that increases ease of use and durability. The hub design enables identical hub bodies to be used for a spreader hub and a rib hub.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention pertains to collapsible umbrellas for personal use as are typically used for protection from the sun. In particular, the present invention is an umbrella including an improved hub design providing easy and durable operation for umbrellas of the larger sizes and weights.  
         [0002]     Such umbrellas are generally known in the prior art. U.S. Pat. No. 5,193,566 to Chen; U.S. Pat. No. 5,247,956 to Vincent; U.S. Pat. No. 6,076,540 to You; U.S. Pat. No. 6,314,976 to Clarke; and U.S. Pat. No. 6,298,867 to Chang disclose various designs which attempt to resolve some of the weaknesses of the collapsible umbrella concept. Particularly, many umbrellas suffer from high weight which makes their manual operation difficult by the user. High weight is a problem directly, and indirectly as producing friction between the relatively moving parts during erection of the umbrella canopy. In addition, as devices often used outdoors in conditions introducing grit and moisture to the umbrella parts, umbrellas are susceptible to corrosion and wear which further hamper operation by users and produce a need for repair. Prior art umbrellas do not provide sufficiently smooth operation for manual operation by single person users, particularly in larger umbrellas. The Vincent patent illustrates one typical design where umbrella ribs and spreaders are pivotably attached at the upright pole by means of wires passing through holes in rib and spreader proximal ends, respectively. While the wires provide an axis of rotation for the moving ribs and spreaders, the rotational friction is inherently high in such a design. In addition, due to the small bearing area between the wire and the rib or spreader hole, high bearing forces produce a high level of wear and deterioration of the parts, increasing the problem. These events are accelerated by environment moisture and grit. In any umbrella design where the bearing area is small at the point of rotation of the ribs and spreaders, bearing and friction forces will likely be a source of problems for the user.  
         [0003]     In addition, the design of prior art umbrellas do not provide for easy disassembly for maintenance or replacement of parts. What is needed is an improved umbrella hub design that provides for durable and low friction movement of the umbrella elements during opening and closing operations of the umbrella and provides for easy maintenance and repair.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention is an improved umbrella and umbrella hub. The inventive umbrella hub incorporates a spherically shaped ball joint knuckle secured to the inner end of the umbrella frame ribs and spreaders. The joint knuckles are received and retained in spherical bearing surfaces to provide pivoting movement of the ribs and spreaders. The joint knuckles have a radial dimension larger than the cross-sectional dimension of the rib or spreader to provide increased bearing area and consequent decreased bearing stresses. This geometry increases durability and life and ease of use. These advantages of the instant inventive design are particularly appreciated in larger umbrellas having a cover extended diameter in the range of six to twenty feet.  
         [0005]     The hub is preferably formed of a flange member and matching face plate that are joined to a sleeve for receiving an umbrella pole. The flange and face plate each include spherical depressions that, when the flange and face plate are joined, define the bearing surfaces retaining the joint knuckles. This configuration may be identically used for both a rib hub and spreader hub to simplify and reduce the cost of manufacture and assembly. In a rib hub, the joint knuckles include a projecting stop post that, through interference with the hub, functions as a rotational stop for the attached rib. The face plate of the preferred hub design is removable for easy maintenance or replacement of parts.  
         [0006]     Additional elements and advantages of the invention are illustrated in the following description of preferred embodiments and the accompanying illustrations.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a perspective view of an umbrella according to the invention incorporating inventive hubs.  
         [0008]      FIG. 2  is an enlarged partial side view of the same embodiment shown in  FIG. 1 .  
         [0009]      FIG. 3  is a perspective view of a preferred embodiment of the inventive umbrella hub including spherical joint knuckles for use as a rib hub.  
         [0010]      FIG. 4  is a perspective view of a preferred embodiment of the inventive hub including joint knuckles configured for use as a spreader hub.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]      FIG. 1  is a perspective view of an umbrella according to the invention. The umbrella includes a center ridge pole  10  which is the main support and which may be, as in the prior art, pointed at its lower end for penetration into the ground. At the top of the ridge pole  10  is attached a collapsible framework  12  which supports a flexible cover  14  (shown partially cut away). The cover  14  may be formed of fabric, plastic, rubber-coated fabric, or similar materials known in the art for providing rain or sun protection. The general construction, cooperation, and operation of the framework  12  and the cover  14  are known in the art. While the embodiment shown in the figure has a framework  12  and cover  14  of overall generally circular geometry, other geometries such as square are also contemplated.  
         [0012]     The framework  12  consists of, essentially, elongated and somewhat flexible ribs  16  and supporting spreaders  18 . The ribs  16  are under, and attached to, the cover  14 , and when fully expanded, stretch the cover  14  to its operational, open, configuration. The spreaders  18  are each pivotally attached at a distal end to a respective rib  16  at a point intermediate between the rib ends, and support the ribs  16  in its operational configurations.  
         [0013]      FIG. 2  is a side view of the same embodiment shown in  FIG. 1  showing the details of the ribs  16  and spreaders  18  and their relative attachments. The cover  14  (see  FIG. 1 ) is removed for clarity. Each rib  16  is attached at a proximal end to a central rib hub  20 . The rib hub  20  is rigidly secured to the ridge pole  10 . The function of the rib hub  20  is to locationally retain the ribs  16  while providing pivotal movement of the ribs  16  about a horizontal axis through the proximal end of each rib  16 . The details of the rib hub  20  and its operation are provided below.  
         [0014]     Each spreader  18  is pivotally attached at its respective proximal end to a central spreader hub  22 . The spreader hub  22  is slidably secured to the ridge pole  10  to allow relative vertical motion of the spreader hub—and the attached spreader ends. The function of the spreader hub  22  is to locate the spreader proximal ends adjacent the ridge pole  10  and provide for vertical movement of the proximal ends to effect the opening and closing of the umbrella. This basic function and operation is similar to that of prior art umbrella structures. The details of the spreader hub  22  and its operation are provided below.  
         [0015]      FIGS. 3 and 4  are perspective views of a preferred embodiment of an inventive umbrella rib hub and spreader hub, respectively. To simplify and reduce cost, the rib and spreader hub bodies  30  are preferably identical. The following discussion pertains to both hubs of the preferred embodiment except where otherwise indicated. In other embodiments, the rib and spreader hub bodies may be dissimilar.  
         [0016]     In  FIG. 3  and  4  the hub body  30  is shown exploded on opposite sides of joint knuckles  50 ,  60 . Each hub body  30  includes a hub cylindrical sleeve  32  having a longitudinal cylindrical bore  33  with an internal diameter sized for slidable engagement with the round ridge pole  10 . The sleeve  32  has a longitudinal length sufficient to provide stability against pivotal rocking of the spreader hub sleeve on the ridge pole. Preferably, the sleeve longitudinal length is at least equal to the internal diameter. The sleeve wall thickness is somewhat dependent on the material of construction and may be easily determined by the designer.  
         [0017]     At the upper extent of the hub sleeve  32  a hub flange  36  extends radially outward from, and perpendicular to, the bore  33 . The hub flange  36  has a circular perimeter, although this particular geometry is not critical. The hub flange  36  has a flat, upwardly directed, flange face  37  that is orthogonal to the bore centerline. Located evenly spaced in a circular pattern about the flange face  37  are a number of spherically shaped cavities or depressions  38 . Herein, the depressions are described as spherical although they are not complete spheres. The term “spherical” includes partial and complete surfaces having spherical shape. In the embodiment shown, there are eight such depressions  38 , although other numbers are also operable. The configuration and function of these depressions are discussed below.  
         [0018]     The hub body  30  includes also a generally disk shaped flange face plate  40  that mates to the hub flange  36 . The face plate  40  has a mating surface with half-sphere depressions  38  sized and configured to mate identically with those of the flange  36 . Upon co-joining of the flange  36  and face plate  40  surfaces, the pairs of respective mating depressions  38  each form a spherical joint cavity. The face plate includes a continuation of the center bore  33 . Slots  42  are cut, or formed, in both the flange  36  and face plate  40 , from their perimeter, radially inward, and entirely through the center of each spherical depression  38 . Each slot  42  extends slightly inward of the respective depressions. The width of each slot is narrower than each depression&#39;s diameter such that four depression portions are part of one spherical surface—two in each of the flange  36  and face plate  40 .  
         [0019]     The function of the depressions  38  is to form a retaining bearing surface for receiving a rib or spreader ball joint knuckle  50 ,  60 . The rib hub  20  and spreader hub  22  have respectively differently configured knuckles and they both will be discussed in subsequent sections herein. However, the following discussion of the configuration of the knuckles  50 ,  60  and the flange depressions  38  apply to both except where otherwise indicated. Each knuckle  50 , 60  is a rigid element having a generally spherical outer surface and having a radius slightly less than the radius of the corresponding depressions receiving the knuckle. In this manner, when a knuckle  50 ,  60  is disposed within depressions  38  and the hub portions assembled, the ball joint knuckles  50 , 60  are free to rotate while being locationally retained to the respective hub  30 . While the size of each knuckle is independent of the others, and each may be different, for obvious practical reasons, they are preferably of a common size and configuration. The depressions should be configured to retain the knuckles in a plane orthogonal to the sleeve bore  33  and hence also the ridge pole  10  long axis.  
         [0020]     Each knuckle  50 , 60  includes an open receptacle  52  as a means of receiving and attaching a proximal end of a rib  16  or spreader  18 . Preferably, each rib  16  and spreader  18  has a circular cross-section and hence each receptacle  52  is cylindrical in shape to securely attach the rib  16  or spreader  18 . Other geometries are also contemplated, including square cross-section ribs  16  and spreaders  18  received in similar cross-section cavities. The center axis of the receptacle  52  passes through, and is centered on, the center of the knuckle  50 , 60  such that a received and attached rib  16  or spreader  18  rotates about the knuckle center when moved in the hub. Once received in a knuckle receptacle  52 , a rib  16  or spreader  18  may be secured to the knuckle  50 , 60  by means of adhesive, rigid fasteners, or other means. Alternatively, each rib  16  or spreader  18  may have a respective integrally formed knuckle  50 , 60  at its distal end.  
         [0021]     The function of the knuckles  50 , 60  and the associated depressions  38 , is to provide enlarged rotation bearing surfaces connecting each rib  16  and spreader  18  to the hub  30 . The enlarged surface reduces bearing stresses and friction which in turn increases durability and ease of operation. “Enlarged” is meant here to be in comparison to a bearing surface that might be provided by a through-shaft passing through a transverse hole in the proximal end of a prior art umbrella rib or spreader. In the present design, the enlarged bearing surface is a consequence of the larger radius of curvature of the knuckle and depression relative to the rib and spreader cross-section.  
         [0022]     To further enhance the ease of use and durability of the device, the hub flange  36 , face plate  40  and knuckles  50 ,  60  are preferably formed of a high density plastic, preferably by molding operations. The depressions  38  and cavities  52  may be molded or milled. The use of such plastics is additionally advantageous in typical use environments, such as sand beaches. The use of plastics—over metals—reduces galling and other degradations typical in use of metal components used in prior art devices. Other materials, such as non-corrosive metals, may also be used in the inventive device without the particular benefits of plastics discussed.  
         [0023]     In operation, the ribs  16  and spreaders  18  rotate about their proximal ends at the hub body  30  to alternately elevate and lower the umbrella cover  14 . To allow this movement when the ribs  16  and spreaders  18  are attached to the knuckles  50 , 60 , the ribs  16  and spreaders  18  pass through the slots  42 . For this reason, the width of the slots must be slightly greater that the width or diameter of the respective rib or spreader. The slots  42  serve the purpose of providing support to the proximal end of an associated rib  16  or spreader  18  with respect to preventing lateral movement and rotation about the respective vertical axis. These limitations are necessary for the preferred operation of the device.  
         [0024]     The rib hub  20  and spreader hub  22  ( FIG. 2 ) differ in the configuration of the particular knuckles received in the respective hub body depressions in assembly. As the spreaders  18  need no limitation on their vertical rotation on the anchoring knuckle, the spreader knuckles  60  may have a smooth outer surface without interruption. However, to provide bending of the ribs as is desired in some umbrellas, the rib proximal ends must be stopped in rotation at a common preset angle that is less than perpendicular to the ridge pole. To enable this function, each rib knuckle  50  has a stop post  54  extending from the exterior surface of the knuckle  50 . The stop post  54  is preferably located 90 degrees from the centerline of the receptacle  52  and extends in a radial outward direction. The knuckle  50  is assembled into a hub with the stop post  54  positioned upward—into the faceplate  40 . In operation, when the ribs  16  reach the desired top-most angle, the stop-posts  54  contact a terminal wall  56  of the hub slot  42  and this interference prevents further rotation of the knuckle  50 . At this point, further elevation of the spreader hub  60  will force a bend in the ribs  16 . This operation of forming a rib bend by force of the spreaders is generally known in the prior art although the present structure for, and method of, stopping the rib proximal end rotation is novel. The interference of the stop post  54  and the terminal wall  56  is dependent on at least the relative location of the terminal wall and the size and geometry of the stop post  54 , and many different geometries are possible to provide the needed function for a particular umbrella design. Similarly, in the embodiment shown, the terminal wall  56  is vertical and includes portions in the flange  36  and the face plate  40 . Other geometries are also contemplated to serve the same function.  
         [0025]     To form an umbrella according to the invention, two identical hubs are provided as discussed above. One is assembled with spherical spreader knuckles  60  to form a spreader hub  22  and one is assembled with rib knuckles  50  to form a rib hub  20 . The rib hub  20  is rigidly secured to the top of a ridge pole  10  by sliding the end of the ridge pole  10  into the sleeve bore  33  and permanently attaching it there. The spreader hub  22  is slid over the lower end of the ridge pole and positioned near the rib hub  20 . The ridge pole  10  should include a means of releasably fixing the spreader hub  22  in an open umbrella position. Ribs  16  and spreaders  18  are attached by securing them to respective hub knuckles  50 ,  60 . The rib hub  20  and spreader hub are rotationally oriented on the ridge pole with pairs ribs  16  and spreaders  18  co-aligned vertically to allow them to be properly connected and operated. A cover  14  is secured to the ribs. The above may occur in various sequences to arrive at the same finished configuration.  
         [0026]     To enable the spreaders  18  to operate as desired, their distal ends are each pivotally secured to a respective rib  16  as shown in  FIG. 2 . This is preferably accomplished using a pivot joint formed of a spherical knuckle configured and retained in the manner discussed above in a clamshell type joint structure removably attached to the rib  16 .  
         [0027]     The hub flange  36  and face plate  40  may be secured together in any of a variety of means. In the embodiment shown, fastener lead holes and counterbores are provided for threaded fasteners which may be easily removed for future maintenance of the hub or replacement of parts such as bent ribs or spreaders. In other embodiments, securing means, both removable and permanent may be used, including rivets, adhesives, and plastic or metallic welding and others. Although the hub flange  36  and face plate  40  are shown in the figures with a planar parting line and faces, it will be obvious that the mating face surfaces may have other geometries while still providing the essential function allowing entry by, and removal of, the knuckles from the flange depressions. The face plate  40  have also be formed of multiple parts, each including a portion of the spherical bearing surface as a removable depression portion.  
         [0028]     In alternative embodiments, both the ridge pole  10  and hub sleeve bore  3  have cross-section geometries other than circular, such as square. These allow the same operation as discussed above. However, for many reasons that will be obvious, a circular cross-section is preferred.  
         [0029]     In alternative embodiments, the rib hub  20  does not include a hub sleeve  32 , but is directly fixed to, or integral to, the ridge pole  10 . The inclusion and use of the hub sleeve  32  with the rib hub  20  is a matter of convenient preference due to the use of the sleeve  32  with the spreader hub  22  and desire to manufacture a single, multi-use part.  
         [0030]     Herein, the words, “up”, “down”, “vertical”, and “horizontal” and similar terms are intended to be interpreted as relative to the figures and embodiments discussed and the associated cooperating elements of the invention and are not intended to be otherwise limiting.  
         [0031]     The preceding embodiments and discussions are provided for example only. Other variations of the claimed inventive concepts will be obvious to those skilled in the art. Adaptation or incorporation of known alternative devices and materials, present and future is also contemplated. The intended scope of the invention is defined by the following claims.