Abstract:
The present invention relates to movable barrier systems, such as a strip door suspension systems, that can be repositioned along the length or width of a room, container, or vehicle, for example, that is temperature controlled. The system saves energy, keeps cargo at a constant temperature, and is safe to the operator.

Description:
RELATED APPLICATION 
   This application is a continuation-in-part application of U.S. patent application Ser. No. 11/486,679, filed Jul. 14, 2006, the entire disclosure of which is hereby incorporated by reference. 

   FIELD OF THE INVENTION 
   The invention relates to moveable strip door suspension systems and methods that provide a barrier that moves along a rail and a roller track in a room or vehicle. The barrier may be positioned and releasably locked into position at any point along the rail/roller track system. In an embodiment, the barrier is a thermal barrier or insect barrier, for example. 
   BACKGROUND OF THE INVENTION 
   Storing, transporting and delivering refrigerated goods requires the use of a room or vehicle equipped with a refrigeration or freezer unit or other means of cooling the air within the room or vehicle sufficiently to protect the cargo. One of the most obvious examples of such cargo is refrigerated or frozen foods or medical supplies which, if allowed to warm or thaw, are no longer useable or saleable. 
   If a vehicle is fully loaded at a single loading site and transported to an unloading site where it is fully unloaded, problems with respect to maintaining a sufficiently cool temperature are not necessarily encountered. However, when a vehicle is not fully loaded and/or is loaded at multiple loading sites and/or unloaded at multiple unloading sites, the risk of loss of refrigeration or increased expense for maintaining a proper refrigeration temperature increases. As delivery proceeds, the vehicle becomes partially emptied. This means that the refrigeration unit then cools not only the remaining cargo, but the empty portion of the vehicle. Each time the vehicle doors are opened and cargo is removed, cool air is lost and the warmer air that replaces it must then be cooled in order to protect the remaining cargo. As a consequence, cargo that is loaded first is also the cargo that is unloaded last and is thus subjected to the full effect of the warming and cooling cycles caused by repeatedly opening and closing the vehicle doors. 
   One approach to maintaining the cooling capacity of a refrigerated vehicle has been to provide a movable bulkhead that can be repositioned along the vehicle&#39;s length. The bulkhead is used to close off that portion of the vehicle that still contains refrigerated goods. However, rigid bulkheads are expensive, complex, difficult to position, heavy, and must be moved each time the goods contained behind them are loaded or unloaded. While some such bulkheads have doors that can be opened, a majority of bulkheads are solid and it is impossible to see precisely what is behind them without first moving them. Further, known bulkheads in the art feature heavy mounting hardware, and are hinged such that the entire bulkhead is lifted and then positioned along the roof of the vehicle when not in use. Such doors are difficult to repair and represent a potential safety hazard should the door hardware fail. 
   Strip curtains that span the width of a vehicle make it possible for a person to walk through the curtain without having to move it to one side and facilitate the on-loading and off-loading of cargo. However, where goods must be loaded in bulk, such as by forklift truck, it becomes extremely desirable to provide a way for the curtain to be moved from its position stretching across the load space to enable free access to the cargo or the cargo space. Without an easily operated structure to enable the movement of such a curtain along the vehicle length and across the vehicle width there is a tendency for the operator to use the strip curtain improperly. 
   Another approach to providing temperature control is a curtain or door, fashioned either from overlapping vinyl strips or insulating “blankets” consisting of fabric sandwiched around an insulating core. The strips or blankets are secured along a horizontally extending overhead member. Vinyl strips are made of lightweight translucent or transparent vinyl material, allowing the cargo behind the strips to be seen, while avoiding the storage and manipulation problems inherent in the use of heavy, rigid bulkheads. Such strip curtains have been modified for use in vehicles by providing a horizontally extending aluminum support member from which the individual strips are suspended, and a track-and-trolley extending along the upper walls of the vehicle proximate the roof, whereby the horizontally extending support member can be positioned at various specific sites along the length of the vehicle (see, for example, U.S. Pat. No. 4,639,031 to Truckenbrodt). However, that patent discloses a locking system that can only engage with a series of holes placed at set intervals along the rail system it employs. In addition, the operator must undo the lock on one end of the system and pivot the system in order to move it to a different position in the vehicle. Such pivoting is difficult and dangerous if the operator is moving the system to the rear of a vehicle, because it requires the operator to leave the vehicle and step onto the ground, a docking board, scissor lift, or fork lift, thereby posing a safety issue. Another type of strip door, such as that manufactured by Kason Industries, is stationary and cannot be moved forward or backward inside a vehicle. Yet another system used in the past involves the permanent installation of a horizontal support member to the vehicle wall at a hinge which allows the strip curtain to be stored along the side wall of the vehicle, but does not allow the curtain to be repositioned along the length of the vehicle. 
   Accordingly, the need exists for a lightweight, ergonomically designed, low maintenance, and flexible thermally insulating barrier that may be positioned at any point along the length of a vehicle, thereby varying the air space required to be cooled, while at the same time providing structure that enables the barrier to be moved to a loading or storage position along side one of the trailer&#39;s side walls. 
   SUMMARY OF THE INVENTION 
   The present invention relates to movable barrier systems that can be repositioned along the length or width of a room, building, container, or vehicle, for example, a truck, trailer, railroad car, aircraft hold, cart, or van. In an embodiment, the room, building, container, or vehicle is temperature controlled (e.g., refrigerated, freezing, or heated). The movable barrier systems and methods do not require pivoting of the barrier to reposition it, thereby making it safer and allowing the operator to stand within the trailer, for example, even when moving the barrier system to the rear of the vehicle. In addition, the movable barrier system provides a wider and higher insulated cargo space. 
   In one aspect, the invention provides movable barrier systems extendable between two side walls. The systems includes a barrier, a transverse bar engaged with the barrier such that the barrier extends between the two side walls, one end of the transverse bar moveably engaged with a first support and a second end of the transverse bar moveably engaged with a second support. The system further comprises a releasable locking mechanism engaged with the first end of the transverse bar and the first support such that the locking mechanism can lock onto the first support, for example, by clamping it. In an embodiment, the releasable locking mechanism can lock onto the first support at any point as it travels along the first support. In an embodiment, the transverse bar is moveable along the first and second support without the need to disengage it therefrom in order to move the barrier. 
   In an embodiment, the barrier is a thermal barrier (e.g., refrigeration or heat), such as a strip door or curtain; however any desired barrier, such as an insect barrier, is contemplated. In an embodiment, the barrier is formed from a plurality of strips, for example, thermoplastic sheeting or mesh. The barrier may be made of any suitable material, e.g., poly vinyl chloride, vinyl, and insulating fabric. 
   In an embodiment, the first support comprises a rail, such as an I or T rail, extending along the first side wall. 
   In an embodiment, the second support comprises a roller track extending along the second side wall. In an embodiment, the barrier system of the invention comprises a transverse bar that is engaged with a roller assembly that engages with the roller track. The roller assembly comprises at least one wheel. 
   In an embodiment, the locking mechanism comprises a moving member for releasing the locking mechanism. The release handle may be, for example, a wand, twist rod, chain, or rope. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features and advantages of the present invention, as well as the invention itself, will be more fully understood from the following description of preferred embodiments when read together with the accompanying drawings, in which: 
       FIG. 1  provides a perspective view of moveable strip door suspension system mounted on a trailer&#39;s side walls according to an embodiment of the invention. 
       FIG. 2  provides a perspective view of a moveable strip door suspension system according to an embodiment of the invention. 
       FIG. 3  provides a perspective view of the releasable locking mechanism according to an embodiment of the invention. 
       FIG. 4   a  provides a top view of the releasable locking mechanism in an open position according to an embodiment of the invention. 
       FIG. 4   b  provides a close up of the cam portion of the releasable locking mechanism of  FIG. 4   a  in an open position according to an embodiment of the invention. 
       FIG. 5   a  provides a top view of the releasable locking mechanism in a closed position according to an embodiment of the invention. 
       FIG. 5   b  provides a close up of the cam portion of the releasable locking mechanism of  FIG. 5   a  in a closed position according to an embodiment of the invention. 
       FIG. 6  provides a top perspective view of a releasable locking mechanism according to an embodiment of the invention including a bump stop that applies pressure to the first support. 
       FIG. 7  provides a bottom perspective view of the releasable locking mechanism of  FIG. 8 . 
       FIG. 8  provides a top perspective view of a releasable locking mechanism according to an embodiment of the invention including a bump stop that applies pressure to the roller and the first support. 
       FIG. 9  provides a side view of a pivot mechanism that will allow the strip door of the invention to be moved to a side of the container or truck. 
       FIG. 10  provides a perspective view of a pivotable strip door suspension system according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows an embodiment of the invention comprising a trailer truck  1  with a temperature control unit (not specifically shown) for keeping the interior of the trailer truck  1  at a uniform temperature (e.g., cool or hot). The trailer truck  1  has a left (first) side wall  2 , a right (second) side wall  4 , a ceiling  6 , and a floor  8 . As shown in  FIG. 1 , a moveable strip door suspension system  10  according to one embodiment of the invention is installed therein. The system  10  comprises a first support  12  disposed on the left side wall  2 , a second support  14  disposed on the right side wall  4 , a strip door  16  attached to a transverse bar  18 , having a first end  20  and a second end  22 , disposed there between, and a releasable locking mechanism  24  for locking the transverse bar  18  in a desirable place along the first and second supports  12 ,  14 . The transverse bar  18  is moveable in both the forward and backward directions and can be locked in place using the releasable locking mechanism  24 , and unlocked and moved as desired. 
   Referring now to  FIG. 2 , the first support  12  is arranged in a fixed parallel spatial relationship with the second support  14 , along the left and right side walls  2 ,  4 . In an embodiment, the first support  12  is an I rail and the second support  14  is a roller track. As shown in  FIG. 1 , in an embodiment, the first and second supports  12 ,  14  are placed proximal to the ceiling  6 , such that the amount of temperature controlled (e.g., cool) air escaping over the strip door  16  is minimized. If desired, additional strip door material or other suitable barrier (not shown) can be attached to the transverse bar  18  or strip door  16  such that it extends upward toward the ceiling  6  to further block the escape of temperature controlled air from the temperature controlled section of the trailer truck  1 . 
   The first support  12  may be any suitable shape for allowing traversal by a releasable locking mechanism  24 . In certain embodiments, the first support  12  may be an I rail, a T rail, beam, cable, or the like. The first support  12  may be made of any suitably rigid material that can withstand the weight and movement stresses of the strip door  16 , for example, metal (e.g., aluminum, stainless steel, galvanized steel, HTP®), plastic, fiberglass, poly vinyl chloride, or the like. In an embodiment, the first support  12  further comprises apertures for bolting or screwing the first support  12  to the left side wall  2  (not shown). 
   The second support  14  may be any suitable shape for allowing traversal by a roller  26  attached to the transverse bar  18 . In certain embodiments, the second support  14  may be a C rail. In other embodiments, the second support  14  is a trolley selected from a flat trolley or an eye manual trolley (e.g., as sold by Vestil Manufacturing Corporation, Angola, Ind.) or a track or the like, such as those sold by Richards-Wilcox, Inc. (Aurora, Ill.). The second support  14  may be made of any suitably rigid material that can withstand the weight and movement stresses of the strip door  16 , for example, aluminum, stainless steel, galvanized steel, HTP®, plastic, fiberglass, poly vinyl chloride, or the like. In an embodiment, the second support  14  further comprises holes for bolting or screwing the second support  14  to the right side wall  4 . 
   In another embodiment, the orientation of the moveable strip door suspension system  10  is reversed such that the first support  12  is secured to the right side wall  4  and the second support  14  is secured to the left side wall  2 . Alternatively, the moveable strip door suspension system  10  is positioned along the length of the vehicle  1 , for example, if the door is located on the side of the vehicle. 
   The strip door  16  may be attached to the transverse bar  18  by any number of securing means.  FIG. 2  shows an embodiment of the invention in which the strip door  16  comprises a number of strips  28  that are attached to the transverse bar  18  by a plurality of bullet shaped members  30 , for example, as in the Maximus System™ or MaxBullet™ mounting hardware sold by Aleco Corp. (Muscle Shoals, Ala.). Any alternative attachment is contemplated, including hooks, buttons, staples, rings, nuts and bolts, welded studs, or the like. The transverse bar  18  may be made of any suitably rigid material that can withstand the weight and movement stresses of the strip door  16 , for example, aluminum, stainless steel, galvanized steel, HTP®, plastic, fiberglass, poly vinyl chloride, or the like. 
   The strips  28  and strip door  16  may be any desired width or length to span a desired space. For example, the strips  28  may be about 2, about 4, about 6, about 8, about 10, about 12, about 14, about 16, about 20, about 25, about 30, about 35, about 40, about 45, about 50, about 55, about 60, about 65, about 70, about 75, about 80, about 85, about 90, about 95, about 100, inches in width or any width there between. The strips  28  may be any suitable length depending on the height of the room, container or vehicle, for example, about 2 feet, about 4 feet, about 6 feet, about 8 feet, about 10 feet, about 12 feet, about 14 feet, about 16 feet, or any length there between. 
   The strips  28  may be made of any useful thermal material, such as, for example, polyvinylchloride, vinyl, vinyl coated fabric, high mass vinyl, pre-coated woven vinyl coated mesh polyester screen, and insulating fabric, and may be clear, opaque, or any desired color, texture, or dimensions. The strips  28  may be any desired thermally insulating thickness, for example, about 0.040, about 0.050, about 0.10, about 0.15, about 0.20, about 0.25, about 0.30, about 0.35, about 0.40, about 0.45, or about 0.50 mm or any thickness there between. Suitable strip  28  material includes, for example, Clear-Flex II®, Hi-Viz®, and Scratch Guard® by Aleco Corp. (Muscle Shoals, Ala.) or Standard Smooth, USDA Low-Temp Smooth, USDA Low-Temp Reinforced, Anti-Static, Weld Screen, Opaque, Safety Orange, X-Low-Temp sold by Kason Industries, Inc. (Lynbrook, N.Y.) or strip doors such as Save-T® sold by TMI Inc. (Pittsburgh, Pa.), Verilon® Vinyl (Wheeling, Ill.), or those sold by Singer Safety Co. (Chicago, Ill.), Wilson Industries (Pomona, Calif.), or Strip-Curtains.com (Point Roberts, Wash.), for example. Alternatively, the strips  28  or strip door  16  may be comprised of a material (e.g., mesh strips) that keeps insects out of a portion of the trailer  1 . In an embodiment, the insect strips  28  are mesh strips made of pre-coated woven vinyl coated mesh polyester screen, such as Air-Flex® sold by Aleco Corp. (Muscle Shoals, Ala.). 
   Referring again to  FIG. 2 , an embodiment of the movable strip door suspension system  10  is shown in more detail. In an embodiment, the first support  12  is I shaped and comprises a first end  31  and a second end  32  comprising a first side  34  and a second side  36 . The first side  34  of the first support  12  is placed against the left side wall  2  and the second side  36  engages with the releasable locking mechanism  24 . The second support  14  is C shaped and comprises a first end  38  and a second end  40  and a side  42  that is placed against the right side wall  4 . The second support  14  is engaged with a roller  26 , for example, such as the rollers sold by Action Industries (Cleveland, Ohio). In an embodiment, the roller  26  may be a utility hanger, caged roller bearing, ball bearing, or the like, such as those sold by Richards-Wilcox, Inc. (Aurora, Ill.). The roller  26  is rotatably engaged with a bracket  44  that is attached to the second end  22  of the transverse bar  18  and the first end  20  of the transverse bar  18  is attached to the releasable locking mechanism  24 . 
   Referring now to  FIG. 3 , in an embodiment of the invention, the releasable locking mechanism  24  clamps onto the first support  12  and is moveable anywhere along the first support  12  between the ends  31 ,  32 . In an embodiment, the releasable locking mechanism  24  is a brake mechanism such as those described in U.S. Pat. Nos. 3,348,632 and 5,238,084 to Swager relating the Climber&#39;s Buddy™ sold by Sur Loc, Inc. (Fremont, Ind.) and US Patent Application Ser. No. 20030217887 to Thomas. The releasable locking mechanism  24  may be spring-biassed into frictional engagement with the first support member  12 . The releasable locking mechanism  24  may be a clamp, such as a girder clamp, a universal superclamp, a swivel or fixed jaw adjustable girder clamp, for example (i.e., as sold by Fastenal, Winona, Minn.), or the like, or other clip, cam, or lock that can move along a track and lock in place along the track. 
   Referring to  FIGS. 3-5   b , in an embodiment of the invention, the releasable locking mechanism  24  comprises side plates  46 ,  48 , between which are disposed rollers  50  and a locking arm  52  comprising a cam  54 . The rollers  50  and the locking arm  52  of the releasable locking mechanism  24  are spaced to engage an H rail  12  and to allow for locking engagement with the cam  54 . In an embodiment, a spring (not shown) is mounted on each side of locking arm  52 , biasing the cam  54  against the H rail  12 . A bolt  56  passes through the side plates  46 ,  48  to secure the releasable locking mechanism  24  to the transverse bar  18 .  FIGS. 4   a  and  4   b  show a releasable locking mechanism  24  in the open position, in which the cam  54  is not pressing against the H rail  12 , and can be moved along the H rail  12  in either direction.  FIGS. 5   a  and  5   b  show the releasable locking mechanism  24  in the locked position, in which the cam  54  is engaged with and locked against the H rail  12 . 
   Referring again to  FIG. 2 , in an embodiment, the releasable locking mechanism  24  further comprises a moving member  58  for use by the operator to grasp and push or pull to open and close the releasable locking mechanism  24 . In an embodiment, the moving member  58  is a wand, a twist rod, a chain, or a rope, for example. In another embodiment, the moving member  58  is a cargo bar or cargo strap that is already in the trailer for keeping the trailer contents securely in place (e.g., those sold by Vestil Manufacturing Corp., Angola, Ind.). The moving member  58  is useful for moving the strip door  16  forward and backward along the first and second supports  12 ,  14 . 
   Referring now to  FIGS. 1-3 , the strip door  16  is initially positioned at a desired location within a vehicle  1 , with transverse bar  18  secured to the first support  12 . When it is desired to move the transverse bar  18  along the length of vehicle  1 , the releasable locking mechanism  24  is opened by moving the locking arm  52  either by hand or using a moving member  58 , for example. While holding the locking arm  52  in the open position as shown in  FIGS. 4   a  and  4   b , the releasable locking mechanism  24  may be moved along the first support  12  and second support  14  to a second desired position, where the locking arm  52  is released and locks in place ( FIGS. 5   a  and  5   b ). The strip door  16  can be moved with minimum force, allowing a user to move the strip door  16  closer to the goods requiring refrigeration, freezing, or heating. In another embodiment, the releasable locking mechanism  24  is moved along the first support  12  pneumatically, according to art known methods, by operation either directly on or around the moveable strip door suspension system  10 , or remotely, e.g., in the cab of a truck by the driver. 
   Referring now to  FIGS. 6 and 7 , in an embodiment of the invention, the releasable locking mechanism  124  clamps onto the first support  112  and is moveable anywhere along the first support  112  between the ends  131 ,  132 . The releasable locking mechanism  124  is spring-biassed into frictional engagement with the first support member  112 . In this embodiment, the releasable locking mechanism  124  comprises a brake mechanism  129 , which comprises two rollers  126   a ,  126   b  and two bump stops  127   a ,  127   b . The bump stops  127   a ,  127   b  comprise a material suitable for frictional engagement with the first support  112  and/or the rollers  126   a ,  126   b , such as rubber or plastic. The bump stops  127   a ,  127   b  are attached to curved pivot arms  180   a ,  180   b , which are bolted to base plate  146  by a bolt mechanism  156   a ,  156   b  (e.g., comprising a nut, a bolt, and a washer). The base plate  146  is bolted to the transverse bar  118  by fasteners  157   a ,  157   b  (e.g., comprising a nut and a bolt). The rollers  126   a ,  126   b  are attached to roller axles  125   a ,  125   b  which are rotatably connected to base plate  146 . A rope  158  is engaged with lever arm  184 . Lever arm  184  comprises ends  186 ,  188 , to each of which a cable connector  190   a ,  190   b  is attached. One end  192   a ,  192   b  of the cable connector  190   a ,  190   b  is attached to the lever arm  184  and the other end  194   a ,  194   b  of the cable connector  190   a ,  190   b  is attached to a spring and cable anchor plate  196 , which is disposed on pivot arms  180   a ,  180   b . One end  200   a ,  200   b  of a side spring  198   a ,  198   b  is attached to the spring and cable anchor plate  196   a ,  196   b  and the other end  202   a ,  202   b  of the side spring  198   a ,  198   b  is attached to a spring anchor plate  204 , which is disposed on the base plate  146 . In an embodiment, one end  208  of a center spring  206  is attached to the spring and anchor plate  204  and the other end  210  of the center spring  206  is attached to the lever arm  184 . The center spring  206  is not required but helps to control movement of the lever arm  184 . The releasable locking mechanism  124  is released by pulling rope  158 , which passes through eye bolt  182 , which is bolted to transverse bar  118 . Pulling the rope  158  pulls the lever arm  184  toward the eyebolt  182 , thereby preventing the bump stops  127   a ,  127   b  from engaging with the first support  112 . Conversely, releasing the rope  158  allows the bump stops  127   a ,  127   b  to re-engage with the first support  112  when the strip door  128  is placed in the desired location along the first support  112 . The releasable locking mechanism  124  may be used on both ends of the transverse bar  118 , i.e., may be engaged with both a first support  112  and a second support. 
   In another embodiment, illustrated in  FIG. 8 , the bump stops  127   a ,  127   b  angled such that they engage with both the first support  112  and the rollers  126   a ,  126   b  when in the locked position. 
   Although not required to release or move the movable strip door suspension system  10  of the invention along the first support  12  and second supports  14 , as it is for the system disclosed in U.S. Pat. No. 4,639,031, in some circumstances the operator may desire to move the strip door  16  to one side of the container or vehicle  1 . In an embodiment, the strip door  16  can be swung out of the way to simplify loading and unloading, in a similar manner to the “The Swinger” produced by Randall Manufacturing (Elmhurst, Ill.). Referring now to  FIG. 9 , the releasable locking mechanism  24  may comprise a hinge mechanism  60  that allows the transverse bar  18  to pivot so that it can be moved to one side of the vehicle. In an embodiment, a pivot hinge mechanism  60  may be provided by making bolt  56  about 0.5 to about 2 inches longer to allow for a nylon sleeve  62 , such as a DryLin®S anodized aluminum shafting or the like, as sold by Igus, Inc. (East Providence, R.I.), to be inserted through transverse bar  18  and fastened with a washer  64  and lock nut  66 . A spanner bushing  68 , such as those sold by Refrigeration Hardware Supply Corp. (Sun Valley, Calif.) or Graphite Metallizing Corp. (Yonkers, N.Y.) will be placed into the hole through which the bolt  56  passes in the transverse bar  18 , allowing the bolt  56  to rotate within the bushing  68 . 
   Referring now to  FIG. 10 , in an embodiment, the first end  38  of the second support  14  is open such that when the roller  26  reaches the first end  38  it travels off the second support  14  and can pivot relative to bolt  56  to be placed along the first side  2  of the vehicle  1 . In another embodiment, an opening can be placed at any point along the length of the second support  14  in order to release and pivot the transverse bar  18  at another location along the second support  14 . 
   In an embodiment, the strip door  16  is pivoted and then secured to a wall of the container or truck, for example, using a wire form hook  70  such as a bent wire hook, S hook, conveyor hook, wire hold down hook, hanging wire form hook, or the like, such as those sold by Marlin Steel Wire Products (Baltimore, Md.) or Keyspan (Fort Lauderdale, Fla.) or other securing device, such as a tie, snap, bolt, bullet fastener, or the like. 
   One of the many advantages of the invention is that, compared to the device disclosed in U.S. Pat. No. 4,639,031, the transverse bar  18  of the moveable strip door suspension system  10  is closer to the ceiling  6 , providing more clearance for loading goods, especially given the angle at which they are loaded from the back of a truck using an angled dockboard. The moveable strip door suspension system  10  can also travel the entire length of a vehicle  1  without requiring the operator to disembark from the vehicle. Further, the instant invention also has the added advantage of providing more usable space for cargo, because it does not include the bar locking assembly of the system disclosed in U.S. Pat. No. 4,639,031. 
   INCORPORATION BY REFERENCE 
   The contents of all cited references (including literature references, patents, patent applications, and websites) that may be cited throughout this application are hereby expressly incorporated by reference. The practice of the present invention will employ, unless otherwise indicated, conventional techniques of strip door manufacturing, which are well known in the art. 
   EQUIVALENTS 
   The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the invention described herein. Scope of the invention is thus indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced herein.