Patent Publication Number: US-7594342-B2

Title: Spherical desiccator

Description:
This non-provisional application claims priority under 35 USC 119(e) of U.S. Provisional Application Ser. No. 60/781,948 filed by Paul Thom, David Landsberger, and Francis Gomes on Mar. 10, 2006. 

   FIELD OF THE INVENTION 
   The present invention relates generally to arrangements adapted for removing moisture, and more specifically, it relates to an apparatus for removing moisture which is capable of withstanding substantial internal pressure. 
   BACKGROUND OF THE INVENTION 
   Arrangements for removing moisture from enclosures are widely used in industries in which products stored must be maintained at a sufficiently low moisture level or content to preserve their functional integrity. The ability to maintain reduced moisture levels is particularly critical in laboratory environments since it is commonly required to store chemicals, materials, and products which are particularly susceptible to moisture damage. Vacuum desiccant devices capable of producing and maintaining a vacuum within the respective working chambers are known in the art. 
   It is also well known that desiccation is limited by the maximum safe working pressure the device can withstand. While a plethora of such devices are known in the art of various designs and configurations, many of them are of less than ideal construction. The ability of a vessel to maintain structural integrity is limited by the rupture strength of the valve and pipe systems and the tensile strength of the walls. This point is usually the point at which there is the lowest tensile strength which limits the usefulness of the entire structure. As the pressure inside the desiccator decreases, the likelihood of rupture increases. 
   Prior art vessels are severely limited in strength as size increases and are problematic to scale up. A sphere, in contrast to all other configurations, is perfectly symmetrical and has an equal distance from the center point to any point on the surface. The true sphere has the smallest surface area among all surfaces enclosing a given volume and it encloses the largest volume among all closed surfaces with a given surface area. 
   While semi-spherical hollow desiccators exist, to the best knowledge of the inventors, no true hollow, spherical desiccators are known in the art. In this respect, the spherical vacuum desiccator device of the present invention substantially departs from conventional concepts and designs of the prior art. By providing a desiccator with a true spherical working or desiccation chamber, it is possible to achieve substantial safety of the device. Any other shape provides weak points at the joints and corners which forces the user not to apply extreme pressure or risk breakage or injury. 
   In the prior art, glue, solder, epoxy, and other binding agents as well as welding, etc. are often required to secure the structural elements of the desiccator together. For example, in the formation of desiccator cabinets and the like, the connecting area between one side and another must be sealed. In a typical box-like structure, there are many engagement areas providing multiple points of weakness, thus making a strong seal difficult. These connecting areas are prone to leakage and may become one of the weakest areas in the device, especially when the body of the desiccator and the interior region thereof are exposed to substantial positive and/or negative pressure conditions. The need to fortify these connecting points and the use of multitude structural elements increases the cost and complexity of such prior art desiccation devices. 
   It is known in the art, such as is disclosed in U.S. Pat. No. 5,807,422 to Grgich, et al, that the lower the velocity of the gas, the closer the dynamic capacity is to the static capacity of the desiccant. As velocity is decreased, the capacity of the desiccant, namely, the ability to absorb liquid from a gas, is increased because the time that the gas is in contact with the absorbent is increased. As the linear gas velocity through the desiccant bed is lowered, the dynamic capacity of the desiccant is increased since the gas molecules are in contact with the absorbent for a greater period of time. Slowing the velocity of the gas may be accomplished by increasing the size of the vessel or decreasing the pressure inside the vessel. This may be accomplished by decreasing the temperature. However, the Grgich device is limited in structure because a true sphere is not disclosed. Further, a hollow area for equal air flow is not disclosed, but rather a spherical desiccant absorption unit composed of zones and so does not solve the present problem of equal air flow and unlimited scalability while maintaining complete structural integrity. While temperature control is also an issue in the Grgich patent due to the limited volume in the absorption bed, this problem has been solved by the present invention by providing a single air cavity structurally designed for equal air flow. 
   Thus, there has been a long felt and unsolved need for a simple, inexpensive, and reliable desiccator capable of withstanding great positive and negative pressure, the desiccator capable of providing a uniform distribution of gas within the working chamber. 
   SUMMARY OF THE INVENTION 
   One aspect of the invention discloses a spherical vacuum desiccator having first and second substantially identical hemispherical shells adapted for mutual engagement with each other. Each hemispherical shell consists of a body with inner and outer hemispherical surfaces and an engaging region provided there between. A receiving segment and a connecting segment are positioned in a spaced-apart relationship within the engaging region. In the assembled condition of the invention the connecting segment of the first hemispherical shell engages the receiving segment of the second hemispherical shell. The inner surfaces of the first and second shells define a substantially hollow operative chamber within the desiccator having a true spherical configuration. 
   As to another aspect of the invention, in each hemispherical shell the engaging region includes a flange extending outwardly from the outer surface and extending circumferentially so as to substantially surround the outer periphery of the respective shell. In each hemispherical shell the connecting and receiving segments form the respective projections extending outwardly from the flange so as to be disposed within the flange opposite to each other. The receiving segment consists of a receiving recess extending inwardly from the outer periphery from the respective projection. On the other hand, in each hemispherical shell, the connecting segment consists of a connecting member extending transversely to the surface of the respective projection. 
   As to a further aspect of the invention, in the assembled condition of the spherical vacuum desiccator, the first hemispherical shell is disposed in an inverted position with respect to the second hemispherical shell in such a manner that the connecting member of one shell engages the receiving recess of another shell forming a hinge connection facilitating pivotal motion between the first and second hemispherical shells. In the assembled condition of the desiccator, the first hemispherical shell can be disposed having the respective interior hemispherical surface and the receiving recess to face upwardly, so as to receive the respective connecting member of the second shell, as to facilitate pivotal motion of the second shell with respect to the first shell. 
   Still another aspect of the invention provides a hemispherical shell for a substantially spherical desiccator which consists of a body with inner and outer hemispherical surfaces and an engaging region positioned there between. A receiving segment and a connecting segment are positioned in a spaced-apart relationship on the engaging region. The engaging region may include a flange extending outwardly from the outer surface and circumferentially so as to surround the outer periphery of the hemispherical shell. The connecting and receiving segments form respective projections extending outwardly from the flange so as to be disposed within the flange opposite to each other. 
   As to still another aspect of the invention, the receiving segment consists of a receiving recess extending inwardly from the outer periphery from the respective projection. The connecting segment consists of a connecting member extending transversely to the surface of the respective projection. 
   Still another aspect of the invention, the longitudinal extension of the connecting member is substantially equal in length to the depth of the receiving recess. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a desiccator of the invention; 
       FIG. 2  is a front elevational view thereof; 
       FIG. 3  is a side elevational view thereof; 
       FIG. 4  is a sectional view according to section line  4 - 4  of  FIG. 2 ; 
       FIG. 5  is a sectional view according to section line  5 - 5  of  FIG. 3 ; 
       FIG. 6  is a top plan view of one embodiment of the hemispherical shell or sectional view according to section line  6 - 6  of  FIG. 2 ; 
       FIG. 7  is a top plan view of another embodiment of the hemispherical shell or sectional view according to section line  7 - 7  of  FIG. 2 ; 
       FIG. 8  is a sectional view showing the desiccator of the invention in a semi-open position; 
       FIG. 9  is an enlarged view showing a pivotal arrangement of  FIG. 8 ; 
       FIG. 10  is a perspective view of another embodiment of the desiccator of the invention; 
       FIG. 11  is a perspective view of a further embodiment of the invention showing one hemispherical shell formed with port sub-assemblies; 
       FIG. 12  is a front elevational view thereof; 
       FIG. 13  is a side elevational view thereof; 
       FIG. 14  is a top plan view thereof; 
       FIG. 15  is a sectional view according to section line  15 - 15  of  FIG. 14 ; 
       FIG. 16  is an enlarged view showing the detail of  FIG. 15 ; 
       FIG. 17  is a partial sectional view showing one embodiment of the glove accessory in an assembled condition thereof; and 
       FIG. 18  is a partial sectional view showing a further embodiment of the glove accessory in an assembled condition thereof. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings in general and to  FIGS. 1-7 , specifically showing a vacuum desiccator  10  of the invention, which is formed by a combination of practically identical first  12  and second  14  shells adapted for mutual engagement with each other. As best illustrated in  FIGS. 4 and 5 , in the preferred embodiment each shell consists of a body  16  having an interior hemispherical surface  18  and exterior surface or portion  20  culminated at one end by respective poles  22 ,  24 , with an engaging interface  26  provided at another end thereof. In the assembled condition the desiccator  10  consists of a first hemispherical cavity  28  and second hemispherical cavity  30 , which are formed by the matching interior substantially hemispherical surfaces  18  of the respective shells. The interior surfaces  28  and  30  of the first and second cavities substantially mirror each other and interlock in an airtight seal at a connecting region  32 , which is equidistantly oriented between the poles of the respective hemispherical cavities. In this manner a hollow, spherical operational chamber  34  capable of withstanding extreme positive or negative air pressure is formed. 
   While the drawings depict exterior portions or surfaces  20  as being hemispherical in nature, this is taught by way of example only. The exterior portion  20  of the desiccator of the invention may be of any conventional configuration such as cubical, tetrahedral, or otherwise polyhedral. The exterior portion may form a unitary structure with the interior surfaces  18  or may be a separate entity which encloses the device partially or fully. 
   As should be readily apparent from the accompanying drawing figures, the first  28  and second  30  hemispheres are substantially identical in structure, and in the assembled state the first hemisphere  12  has an inverted orientation with respect to the second hemisphere  14  and vise versa. Consequently, the desiccator assembly is depicted in a vertically oriented manner throughout the drawings. 
   In each shell the engaging interface  26  includes an engaging flange  38  extending in the plane dissecting the interior and exterior surfaces. In the preferred embodiment the engaging flange originates from the hemispherical inner surface  18 , passes through the body  16  and extends outwardly from the exterior portion or surface  20  circumferentially, so as to substantially surround the exterior periphery of the respective shell. The engaging interface  26  of each shell also includes connecting  40  and receiving  42  segments in the form of respective projections which are spaced apart from each other and extend outwardly from an outer periphery of the engaging flange. A receiving recess  46  is provided in the receiving segment  42  extending inwardly from the outer periphery of the respective projection. On the other hand, in each shell, the connecting segment  40  includes a connecting member  44  extending transversely to the surface of the respective projection. The connecting segment  44  of the first hemispherical shell is configured for engagement with the receiving recess  46  of the second hemispherical shell. 
   The engaging interface  26  of each shell further includes first  48  and second  50  clamping regions which are spaced from each other and extend outwardly from the rear face of the engaging flange  38 . Referring now to  FIGS. 1 and 8  depicting the first clamping region  48  extending between front  52  and rear  54  ends thereof. The rear end  54  is connected to the exterior portion of the shell, whereas the front end  52  is open. Structurally the first clamping region  48  is defined by first  56  and second  58  spaced from each other supporting walls interconnected by a connecting wall  60 . The supporting walls extend outwardly from the rear face of the engaging flange, so as to define a substantially hollow clamping cavity  62 . The previously discussed receiving segment  42  of the respective projection forms a part of the first clamping region situated between the first  56  and second  58  supporting walls. More specifically, in one embodiment of the invention, the receiving recess  46  extends inwardly from the outer periphery of the projection disposed between the first  56  and second  58  supporting walls. Tying holes  64  are formed within the engaging flange  38  projections and in the close vicinity of the respective supporting walls. 
   The second clamping region  47  is structurally similar to the above-discussed first clamping region. However, instead of the receiving recess, the connecting member  44  extends transversely from the front portion of the engaging flange disposed between the respective first and second supporting walls. 
   In the assembled condition of the spherical vacuum desiccator, the first shell is disposed in an inverted position with respect to the second shell in such a manner that the interior surfaces of the first and second shells define a substantially hollow operative chamber  34  within the desiccator having a true spherical configuration. Furthermore, the connecting member  44  of one shell engages the receiving recess  46  of another shell forming a hinge connection  66  facilitating pivotal motion between the first and second hemispherical shells. In the preferred condition of the desiccator, the second hemispherical shell  14  is disposed having the respective interior hemispherical surface  18  and the connecting member  44  to face upwardly, so as to engage the respective receiving recess  46  of the first shell  12  shell and to enable pivotal motion of the first shell with respect to the second shell. To facilitate such engagement the longitudinal extension of the connecting member  44  is substantially equal to the depth of the receiving recess  46  of the receiving segment. 
   In operation of the invention, while the desiccator is being transferred from an open to closed position and vice versa, the first hemispherical shell  12  moves pivotally with respect to second shell. To assure proper engagement in this motion at least a portion of the second clamping region including the connecting member  44  is received within the inner cavity  62  formed between the first  56  and second  58  supporting walls of the clamping region. 
   As best illustrated in  FIGS. 6 and 7 , the engaging flange  38  of each shell includes a substantially flat base surface  68  with a groove or recess  70  is positioned substantially centrally therein and extends inwardly in to the body of the shell from the base surface. While the above-discussed preferred embodiment of the invention discloses the engaging region of the hemispherical shell having one groove, this teaching is by way of example only. Engaging regions of the shells having multiple grooves adapted to receive multiple respective sealing gaskets are within the scope of the invention. The motive for doing so is to create a stronger seal between the matching hemispherical shells of the desiccator. 
   Each shell can be formed with a port  72  passing through the body thereof, so as to provide communication between the working chamber and an outside source of positive or negative air pressure. 
   Turning now to  FIGS. 4-9 , a supporting arrangement  74  can be provided within the working chamber  34  in the form of multiple projections  75 , spaced from each other and extending outwardly and circumstantially from the interior surface  18  of at least one shell. The main objective of the arrangement  74  is to support a shelf  77  (shown in phantom) which is adapted to accommodate a substance which is subjected to the desiccation process. A desiccant, such as a silica gel, for example, is positioned at the bottom of the working chamber below the shelf. In this manner an air flow can be established within the desiccation chamber between the substance and the desiccant through the perforation formed within the shelf. To accommodate various products which can be subjected to the desiccation process, the position of the shelf  77  within the working chamber  34  can be adjusted. In the invention this is accomplished by means of providing the supporting arrangement  74  having the projection  75  which is disposed within the chamber  34  at different elevations. 
   In this manner it is best illustrated in at least  FIGS. 4 ,  5 ,  8 , and  9  that the supporting arrangement  74  consists of a plurality of supporting subassemblies. Each subassembly is defined by multiple spaced from each other projections  75  extending from an interior of the semispherical shell, so as to define a substantially circular formation. Diameters of circular formations vary depending upon their location within the hemispherical shells. In the supporting arrangement, the circular formations are disposed within planes substantially parallel to each other. In the preferred embodiment, the planes of the supporting subassemblies are parallel to a plane of an engaging flange of the respective shell. 
   A similarly constructed spherical desiccator, that is, a desiccator having a true spherical working chamber and made from the same material and of the same volume and wall thickness, has the lowest described stress on all points within the device. Further, the desiccator having a true spherical working chamber can be made of a thin-walled structure without need for costly reinforcements even as the desiccator is scaled-up to larger sizes due to the efficient design. 
   Each clamping region is formed with at least one tying hole  64  passing through the respective projections  40 ,  42 , so as to provide a hole large enough to tie the shells together through the use of string, rope, metal attachment apparati, or other devices. The typing holes are typically situated on the projections  40 ,  42  at a point exterior to the respective supporting walls  54 ,  56  of the clamping regions. However, the typing holes may be placed anywhere on the projections or in the engaging flange. 
   A supportive structure  80  is provided at the polar region of each shell  12 ,  14 . The supportive structure  80  can be formed having substantially cylindrical configuration with a diameter large enough to stably support the assembled device  10  on a substantially flat surface such as a laboratory table. The diameter of the cylindrical support  80  is typically great enough to circumscribe reasonable area of the outer portion of the desiccator. In the preferred embodiment the supportive structure forms a unitary assembly with the respective hemispherical shells. However, a desiccator where the supportive structure is independent from the shell is also contemplated. 
   In the embodiment of the invention illustrated in  FIG. 10 , the supportive structures  82  are in the form of separate are detachable members. Such members should retain at least the characteristics of the cylindrical supports  80 , that is having a proper height, width, and periphery to support the device  10  on a substantially flat surface. While substantially cylindrical supports  80  have been discussed hereinabove, this has been taught by example only. It should be noted that any conventional configuration of the support structure is within the scope of the invention. The body of the shells is typically made of a solid plastic or any other deformable material. Alternatively, to enable an observer to view the process taking place within the working chamber, the body of the shells can be made from a transparent material. 
   Simplification of manufacture and reduced cost of production is an important objective which exists in the field of desiccators. While many desiccators are known in the art, very few of them are inexpensive and simple to manufacture and assemble. In the present invention this important goal is accomplished by utilizing a combination of the first  12  and second  14  substantially identical shells having interior hemispherical cavities  28  and  30  respectively to form a single element having a true spherical internal working chamber  34 . 
   The true spherical substantially hollow internal working chamber  34 , in contrast to all other configurations, is perfectly symmetrical and has an equal distance from the center point to any point on the surface. The true sphere has the smallest surface area among all surfaces enclosing a given volume and it encloses the largest volume among all closed surfaces with a given surface area. 
   The true spherical internal working chamber  34  solves the long recognized problem of uniform desiccation of a gas. The position and velocity vectors of a point traveling on a sphere are always orthogonal to each other. Therefore, any molecule moving within the true spherical working chamber  34  will move in a similar fashion to every other molecule. The result is equal desiccation without the formation of stagnant or even slowed air pockets which leads to inefficient drying. It is also well known that the effectiveness of desiccation is limited by the amount by which air pressure within the desiccation device can be lowered. The lower volume of air subjected to the desiccation process, the less moisture to be absorbed by the desiccant. In this respect, since the true spherical configuration of the working chamber  34  provides the smallest surface area, it contains less air then the prior art chambers having different configuration. Thus, the greater efficiency is achieved by the invention, since less moisture should be absorbed during the desiccation process. 
   The true spherical operational chamber  34  results in equal pressure at any given point within the desiccator thereby allowing for the greatest positive or negative pressure available for a desiccator constructed of similarly made structural elements having with similar thickness of walls. Further, structural integrity of the true spherical operational chamber  34  remains intact when a sphere is scaled upwards or downwards. Thus, the desiccator of the present invention having true spherical operational chamber  34  may vary in magnitude to a much greater degree than desiccators known in the art. Therefore, this invention should satisfy the long felt need of laboratories for simple, inexpensive, truly efficient, strong, and safe desiccators. 
   The present invention comprises two identical and structurally unitary pieces. Thereby, the present invention accommodates various requirements of various types of laboratories. Such accommodation is achieved primarily because the desiccator can be custom configured for varying laboratory needs in a relatively simple, quick and efficient manner. By merely selecting the required desiccation needed, calculations can be made to determine the size of the desiccator and strength for which it must withstand. The material for constructing the device is thereby selected and the clamping region is contracted or enlarged and the requisite number of grooves added to create the structure necessary for varying laboratory needs. A desiccator can thus be provided having various holding capacities to accommodate various equipment and products positioned therein. Moreover, the identical and separable structure substantially simplifies shipment, storage and assembly of the desiccator. 
   The present invention provides a new and improved desiccant device of a spherical shape which can be made with commonly available materials for easy and efficient manufacture. While polymers, plastics, and glass are all suitable materials, any durable and reliable material capable of maintaining structural integrity while exposed to varying degrees of pressure is suitable for the apparatus. 
   Referring now to  FIGS. 11-18 , illustrating a further embodiment of the hemispherical shell of the invention. As best illustrated in these figures the top shell consists of a body having an interior hemispherical surface  118  and exterior surface or portion  120 , with an engaging interface provided at the lower end thereof. In the assembled condition, similar to the above-discussed embodiments, the desiccator  110  consists of a first hemispherical cavity  128  and second hemispherical cavity  130 . The interior surfaces  128  and  130  of the first and second cavities substantially mirror each other and interlock in an airtight seal at a connecting region  132 , which is equidistantly oriented between the poles of the respective hemispherical cavities. In this manner the hollow, spherical operational chamber  134  is formed. 
   The top hemispherical shell is formed with at least two port sub-assemblies  140  and  142  provided in a central area of a front region of one hemisphere. In the preferred embodiment each port assembly is formed having a coupling unit  141 . As best illustrated in  FIGS. 17 and 18 , each coupling unit consists of a coupling sleeve  144  extending outwardly from a connecting flange  146  which is defined by an exterior convex surface  148  and an interior concave surface  150 . The sleeve  144  is typically formed having a substantially cylindrical configuration, whereas the convex surface  148  and the concave surface  150  are adapted to engage the wall of the respective semi-spherical shell. In this respect, it is illustrated in  FIG. 17  that in one embodiment of the invention, the exterior convex surface  148  is adapted to engage an interior hemispherical surface  118 . In this embodiment, the sleeve  144  extends from the interior area of the desiccator outwardly so as to provide an adequate area for receiving a respective portion of the glove. In the embodiment of  FIG. 18 , the concave interior surface  150  of the coupling sleeve engages the exterior hemispherical surface  120  of the respective shell. 
   The coupling unit  141  can be manufactured independently from the desiccator and is attached to the shell by any conventional means. On the other hand, the coupling unit  141  can be formed as an integral part of the shell. 
   The coupling unit  141  forms part of a glove box accessory adapted to provide a controlled environment for testing and material handling operations. The interior of the desiccator forms an enclosure configured to permit substances to be introduced into or removed form the enclosure. The spherical walls of the desiccator can be formed from a transparent flexible material such as, for example, polyvinyl chloride (PVC) or LEXAN. This arrangement allows users to view and handle substances situated in a controlled or contained environment of the operational chamber  134  of the desiccator. Hand entry into the operational diameter  134  is customized to end-user needs by selecting any type of gloves, such as the bellows-type glove, economy sleeve glove, etc. The coupling sleeves  144  are utilized for providing a secure connection with the respective gloves. 
   A glove  156  for protecting the hand are fixed in a detachable manner to the respective sleeve  144 . As conventional in the art, the gloves  156  are made of a flexible material such as rubber. The sleeve and an upper portion of the glove are joined in a gas-tight manner to the respective coupling sleeve. 
   A retaining element  152  is provided for restraining the glove  156  relative to the desiccator walls when the hand is being removed from the glove. Thus, removal of a hand from the respective glove will not result in the glove being turned inside-out and accordingly, the glove will remain in proper position for insertion of the hand into a glove when usage of the glove is next desired.