Beverage dispenser

Information

  • Patent Grant
  • 5368198
  • Patent Number
    5,368,198
  • Date Filed
    Wednesday, March 10, 1993
    31 years ago
  • Date Issued
    Tuesday, November 29, 1994
    30 years ago
Abstract
A beverage dispenser having a flat carbonator along one end of an ice bank cooled water bath tank. A plurality of syrup coils are arranged along an interior surface of the carbonator. An evaporator extends around a central perimeter of the water bath tank creating a central opening through which an agitator shaft and blade extend for operation by an agitator motor. The agitator shaft extends at an angle into the tank for directing a flow of water towards the carbonator. The tank includes ridges on a bottom surface thereof for directing water upward towards the carbonator and syrup coils and away from a bottom perimeter of the ice bank.
Description

BACKGROUND
FIELD OF THE INVENTION
The present invention relates generally to carbonators for use with beverage dispensing equipment, and more particularly, to integral carbonators submerged in the cold water bath or ice bin of such beverage dispensers.
BACKGROUND OF THE INVENTION
Carbonators are well known in the art, and provide for combining water and carbon dioxide for the production of carbonated water. Such carbonators are typically used in beverage dispensing devices wherein the carbonated water they produce is combined in a post-mix beverage dispensing valve with a syrup for production of a carbonated beverage. Beverage dispensing machines generally provide for cooling of the liquid drink constituents through the use of a cold plate cooled by a volume of ice, or mechanically by a refrigeration system including an evaporator submerged in a water bath around which evaporator a bank of ice is formed. Heretofore, it has been known to submerge the carbonator either in the liquid water bath of a ice bank type machine or placed in the ice bin of a cold plate device. A draw back with the use of the carbonator within an ice bin or cold water bath concerns the volume of such interior space devoted to the carbonator. Since carbonators are pressurized to provide for the carbonating of the water, they are typically a cylindrical pressure vessel. As a result thereof, the carbonator can significantly detract from the size of the ice bank or the volume of ice held in the particular beverage dispenser.
A further problem in beverage dispensing, indirectly related to carbonators, concerns what is referred to in the industry as a "casually drawn" drink. If a beverage valve is not used for a period of time to dispense a drink, the carbonated water existing in the line connecting the valve to the carbonator can become warmed. Thus, the first drink drawn from such a valve, after a lapse of time, can be unacceptably warm due to the heating of the carbonated water.
Therefore, it would be desirable to have a beverage dispensing device that provides for a carbonating strategy that provides for a space efficient carbonator, and that greatly reduces the problem of warm casually drawn drinks.
SUMMARY OF THE INVENTION
The present invention concerns a low profile or flat carbonator for use in a beverage dispensing device. The carbonator includes a front and a rear half, each separately cold drawn from a suitable sheet metal stock. Each half includes a plurality of alternating seams and ridges, and is secured to the other around their respective perimeters and along each seam. The seams do not extend the entire length of the carbonator, thus, the joined halves define an enclosed perimeter volume area and a plurality of enclosed column areas. The column areas are in fluid communication with the perimeter volume and are defined by the ridges of both halves. A top edge of the tank includes fittings for a pressure relief valve, a carbon dioxide inlet, a water inlet, and a level sensor. A plurality of carbonated water lines are equally spaced along and extend from a bottom edge of the carbonator tank. In particular, each carbonated water line extends upwardly, closely adjacent one of the halves of the carbonator and up and over the carbonator top edge.
The present invention can be used in an ice bank cooled beverage dispenser, wherein the carbonator is positioned in the water bath tank in a vertical orientation along one end thereof, and desirably, along the end thereof closest to the beverage dispensing valves. In this use, it can be appreciated that the water bath provides for cooling of the entire carbonator, and moreover, its narrow profile, that is, the spreading of its volume over a relatively flat large surface area, provides for efficiently using the water bath interior volume. In addition, the carbonated water lines coming up along a side of the carbonator are also cooled and then can be plumbed directly to the beverage dispensing valves. Thus, a very small length of carbonated water line remains outside of the water bath, so that only a small volume of carbonated water will be warmed during any long lapse of beverage dispensing from a valve. In addition, by directly plumbing each carbonated water line to a valve, the use of a carbonated water manifold, typically located adjacent the valves to distribute carbonated water thereto from a single incoming line source, is eliminated.





DESCRIPTION OF THE DRAWINGS
A further understanding of the structure and operation, objects and advantages of the present invention can be had by referring to the following detailed description which refers to the following figures, wherein:
FIG. 1 shows a perspective view of the present invention.
FIG. 2 shows a top plan view along lines 2--2 of FIG. 1.
FIG. 3 shows a partial cross-sectional side plan view along lines 3--3 of FIG. 2.
FIG. 4 shows an end plan view long lines 4--4 of FIG. 3.
FIG. 5 shows a cross-sectional view of the present invention along lines 5--5 of FIG. 3.
FIG. 6 shows a side plan partial cross-sectional view of an ice bank cooled beverage dispenser with the carbonator of the present invention contained therein.
FIG. 7 shows a top plan view along lines 7--7 of FIG. 6.
FIG. 8 shows a side plan partial cross-sectional view of an ice cooled cold plate type beverage dispenser with the carbonator of the present invention therein.
FIG. 9 shows a perspective view of a further embodiment of the carbonator of the present invention.
FIG. 10 shows a cross-sectional view along lines 10--10 of FIG. 9.
FIG. 11 shows a side plan partial cross-sectional view of a drop-in type ice cooled cold plate beverage dispenser with the carbonator embodiment of FIG. 9 retained within a vertical portion of an L-shaped cold plate.
FIG. 12 shows a perspective view of a further embodiment of the carbonator of the present invention.
FIG. 13 shows a partial cross-sectional top plan view along lines 13--13 of FIG. 12.
FIG. 14 shows a side plan view along lines 14--14 of FIG. 12.





DETAILED DESCRIPTION
The carbonator of the present invention is seen in FIGS. 1-5 and generally is referred to by the numeral 10. As seen therein, carbonator 10 includes a first half 12 and a second half 14. Halves 12 and 14 are made from a suitable sheet metal such as 18 gauge stainless steel. In particular, they are cold drawn to form an alternating pattern of seams 16 and ridges 18. Halves 12 and 14 are welded together around their respective perimeter edges having top and bottom perimeter edge portions 20 and 21 respectively and side edge portions 22, and along corresponding seams 16, to form the carbonator tank 23. It can be seen that tank 23 includes a top tank volume area 24, a bottom area 26 and a plurality of vertical column areas 28. The top and bottom areas 24 and 26 provide for fluid communication between the columns 28. A top end 29 of tank 23 includes a pressure relief valve 30, a carbon dioxide inlet fitting 32, a water inlet fitting 34 and a level sensor fitting 36 for retaining a level sensor 38. Sensor 38 includes a high level sensing contact 38a, and a low level sensing contact 38b that are connected by a pair of wires (not shown) to an appropriate control means. A J-tube 41 is secured to fitting 34 and extends within a column 28.
A plurality of carbonated water lines 42 extend from a bottom end 43 of tank 23 and include vertical portions 42a that travel upwardly closely along and adjacent second half 14 and then extend with horizontal portions 42b over end 29 and outwardly therefrom in a direction towards side 12 and terminate with beverage valve fittings 44.
As is seen by referring to FIGS. 6 and 7, carbonator 10 is shown in an ice bank type of beverage dispenser 50. As is known in the art, dispenser 50 includes an insulated water bath tank 51 having a bottom surface 51a, a front surface 51b, and rear surface 51c and two side surfaces 51d. A plurality of evaporator coils 52 are held substantially centrally within tank 51 and substantially below a surface level W of water held in tank 51 for producing an ice bank 53 thereon. Carbonator 10 is located within tank 50 and adjacent a front end 54 of dispenser 50. In particular, dispenser 50 includes a plurality of beverage dispensing valves 55 secured to the front end 54. It can be understood that carbonated water fittings 44 allow lines 42 to be hard-plumbed directly to each valve 55. Dispenser 50 also includes a removable plate 56 that provides access to a space 57 between plate and tank 50. A water delivery line 58 is connected to a source of potable water and routed through space 57 to a water pump 59. Pump 59 pumps water through a line 60 to carbonator 10. The majority of the length of line 60 consists of a serpentine coil 60a submerged in tank 50 to provide for cooling of the water flowing there through. Coil 60a is arranged in four convoluted or serpentine portions centrally of evaporator coils 52. Evaporator coils 52 are, as is known in the art, connected to a refrigeration system. Specifically, the refrigeration system main components include, a refrigeration compressor 61 secured to a top deck floor 62, a condensor 63 held by a support and air directing shroud 64 above a cooling fan 64a operated by a motor 64b. An agitator motor 65 includes a shaft 65a and a turbulator blade 65b on an end thereof, and is secured at an angle to floor 62 by an angled support 65c. A carbon dioxide gas delivery line 66 is routed through space 57 and is connected to gas inlet 32. Each valve 55 is connected to a syrup line 67. Lines 67 each have an end portion 67a extending through space 57 for connecting to a source of syrup, and then consist of a middle portion comprising a plurality of loops 67b positioned closely adjacent carbonator 10 in tank 51. Lines 67 then terminate by direct hard plumbing to valves 55 as end portions 67c thereof come up and over carbonator top end 29. Tank 51 includes a front ridge 68, and a U-shaped ridge 69, both integrally molded into bottom surface 51a thereof. Ridge 68 consists of three linear sections and each includes an angled side surface 68a and a vertical side surface 68b, and the three sections extend in a line across the width of tank 51 from one side 51d to the other. Ridge 69 has two parallel components 69a extending in a direction from dispenser front end 56 to the rear end opposite therefrom, and a component 69b perpendicular thereto and extending there between forming the "U" shape. Ridge portion 69a and 69b each include a vertical side edge portion 69c that extends transversely to tank bottom 51a.
It can be understood that carbonator 10 can be of various dimensions to fit the particular dispenser and to provide for the desired volume or capacity. In one embodiment of the present invention, carbonator 10 is substantially rectangular having a tank length, between side edges 22, of approx. 16 inches, and each column 28 has a height, between edges 20 and 21 of approx. 10.5 inches and a diameter, between corresponding ridges of halves 12 and 14, of approx. 1.25 inches, providing for an overall carbonator interior volume of approx. 65 ounces. It can be appreciated that the multiple seams 16 provide for the structural strength necessary to make a container that is relatively flat, that is, has a width that is proportionately less than the height or length thereof, and able to safely withstand the operating pressures of typically 100 pounds per square inch. Thus, carbonator 10 is designed to spread its volume over a larger surface area than standard cylindrical carbonators, but do so in a manner that it can be efficiently packaged into a water bath with the minimum impact on the useable interior volume thereof. Moreover, it can be appreciated that the relatively large surface area of carbonator 10 provides for efficient and rapid cooling of the carbonated water contents thereof, and such surface area is enhanced by the washboard surface created by ridges 18 and seams 16.
In operation, carbonator 10 is connected to a source of pressurized carbon dioxide gas by line 66 and water enters carbonator 10, by operation of pump 59, through J-tube 41 and fills tank 23 until sensor 38a is in contact with the water indicating a full level at which point the control means stops the operating of pump 59. Thus, as in conventional carbonators, water is mixed with carbon dioxide gas under pressure thereby forming carbonated water. As is known, when both contacts 38a and 38b are not in contact with water the control means signals for pump 59 to operate and fill carbonator 10 with additional water until contact 38a is again immersed in water. It can be appreciated that the majority of the length of lines 42 are cooled directly by immersion in the water of bath 51, and only a short remainder thereof, primarily section 42b, extends out of the water bath. Thus, only a relatively small volume of carbonated water will be subject to warming, and such warming can be mitigated by an insulation layer over that portion of line 42 extending out of the water of bath 51. This argument also applies to syrup lines 67, as they are substantially immersed in a cold water bath. Moreover, the portions of lines 42 and coils 67 that extend out of bath 51 are, of course, in an air space generally cooler than that of the surrounding ambient conditions. Thus, providing the water bath has an ice bank, there will always be a good reserve of cold carbonated water, and the problem of carbonated water and syrup warming associated with a casually drawn drink, is greatly minimized.
It can also be seen that the flat carbonator 10 in combination with the particularly configured elongate oval syrup coils 67b lying directly adjacent and along a side thereof, form a cooling coil-carbonator structure that provides for very efficient utilization of the interior volume of tank 51. In addition, water coils 60a can occupy a somewhat larger percentage of the center of tank 51 than would be the case, as in prior art dispensers where the syrup coils thereof also occupy the tank center. Thus, the present invention can always provide for a large volume of cold water for carbonating, and therefore enhances the ability of dispenser 50 to provide for the dispensing of a large volume of adequately cooled drinks at high dispensing rates. A further feature of the present invention concerns the agitator motor 65 being mounted at an angle wherein water in tank is circulated in the direction indicated by the arrows in FIG. 6. Specifically the water is directed towards carbonator 10 and coils 67b. Such movement is enhanced by ridge 68 wherein side 68a thereof serves to deflect such water flow generally upwardly. Ridges 68 and 69 serve to prevent erosion of the bottom of ice bank 53 wherein surfaces 69c thereof serve to block any flow of water in such direction, as also seen by the arrows in FIG. 6. In this manner ice bank 53 is more evenly formed on evaporator coils 52, as opposed to having areas of erosion. An evenly formed ice bank can generally grow to be of maximum volume, hence cooling capacity, and provides for more consistent cooling operation of dispenser 50. It can be understood that ridge edge 68b also serves to retain syrup coils 67b closely adjacent carbonator 10.
As seen in FIG. 8, a beverage dispenser 70 of the cold plate type is shown. In such a dispenser 70 a cold plate 71 is typically located at the bottom of an ice containing bin 72. An example of an ice bin and the securing thereof to a cold plate is seen in U.S. Pat. No. 4,958,505, the contents of which patent is incorporated herein by reference thereto. The particular plate 71 includes an upturned edge 71a to which a liner 73 is secured thereby creating in conjunction with plate 71 the ice retaining area or bin 72. Carbonator 10 can be located within bin 72 and in contact with ice 74, and lines 42, as with dispenser 50 above, directly secured to beverage dispensing valves 60. Thus, carbonator 10 also efficiently distributes its volume in an ice bin as well, and, providing there is sufficient ice therein, also greatly minimizes the effects of carbonated water warming resulting from a casually drawn drink. Dispenser 70 also includes access cover 56 and space 57. As is known in the art plate 71 includes a plurality of serpentine coils (not shown) for containing the various beverage constituents such as syrup and water for pre-cooling thereof prior to delivery to the valves 60. In dispenser 70 plate 71 includes a coil line 76 for pre-cooling flat water prior to delivery to carbonator 10. Line 76, after flowing through plate 71, can extend out of plate 70 and through bin 72 for connecting to inlet 34.
As seen referring to FIGS. 9 and 10, a further embodiment of the carbonator of the present invention is seen. In this embodiment carbonator 80 has halves 80a and 80b secured around a perimeter edge 82. However, unlike carbonator 10 halves 80a and 80b are not convoluted in any manner, rather they are flat. Furthermore, halves 80a and 80b are not secured together at any point or points interior of edge 82. Thus, carbonator 80 has one unobstructed interior volume space 84. Carbonator 80 includes a plurality of carbonated water lines 86. Lines 86 extend externally from top end 88 and extend internally into volume 84 terminating closely adjacent a bottom end 90. Carbonator 80 can also optionally have an extended perimeter webbing 92 around the sides and bottom thereof. Webbing 92 can be used wherein carbonator 80 forms a fourth side of a ice-bin liner. Thus, as per the ice cooled unit of FIG. 8, webbing 92 would fit into edge 71a along the bottom thereof and an alternate liner 94, seen in FIG. 10, would be secured to the remainder of edge 71a and to webbing 92 along flange ends 94a thereof. The operation of carbonator 80 is the same as that for carbonator 10 except that the carbonated water is delivered by lines 86 from the top of carbonator 80. It can be appreciated by those of skill that carbonated water lines 86 could also be used in place of lines 42 in carbonator 10. An embodiment of the present invention using lines 42 will have a little more flexibility in the connecting of such lines to the valves 60 as line 42 can be moved or bent more easily than lines 86 which are shorter and more rigid. Also, an embodiment of the present invention using the strategy of lines 42 is somewhat less complicated structurally on the top end thereof. It can be appreciated that carbonator 80 will have to be made of a thicker gauge material than carbonator 10 to withstand the same internal pressure, even in low pressure applications of 30-60 pounds per square inch useful for certain low carbonated drinks and the like.
Another strategy for pressure containment is seen by referring to FIG. 11, which shows a drop-in type beverage dispenser 100, known in the art, that is typically ice-cooled, and "dropped into" a countertop 102. Dispenser 100 includes an L-shaped cold plate 104 of the type seen in co-pending application Ser. No. 07/960,806, which application is incorporated herein by reference thereto. Cold plate 104 is held within an insulated ice retaining bin 105 which defines an ice retaining space 105a for retaining ice 106 therein, and includes a horizontal portion 104a and a vertical portion 104b. Carbonator 80 is shown cast into vertical portion 104b. Thus, the cast metal, typically aluminum, when hardened, serves to provide an external means of strengthening carbonator 80 against failure as the result of high internal pressures. Lines 86 can then run directly and internally through a tower 107 for direct connection to beverage valves 108. In addition, the portion of lines 86 external of plate portion 104b can be insulated with a suitable insulation material 110. As is known, plate 104a includes serpentine coils of tubing for cooling beverage constituents. A coil line 112 is connected to a source of potable water and a water pump, (not shown) and first extends through plate 104a and then upwardly through plate portion 104b for ultimate connection to water inlet 34. A carbon dioxide gas line, (not shown), is routed through bin 105 and space 105a for connection to inlet 32 of carbonator 80. In operation, carbonator 80 of dispenser 100 is cooled by heat exchange with ice contained within bin 105 and thereby efficiently and rapidly cools the carbonated water therein. Also, as the lines 86 are cooled by heat exchange with portion 104b and are themselves insulated, unwanted heating as the result of infrequent drink dispensing is greatly reduced.
It can be appreciated that carbonators 10 and 80 could be interchanged in the various applications shown herein, and the lines 42 and 86 could be interchanged. Furthermore, it can be understood that carbonators 10 and 80 eliminate the need for a carbonated water manifold structure typically found adjacent the dispensing valves of a beverage dispenser. Such a manifold structure typically receives carbonated water from a carbonator along one line and then has a plurality of outlets for delivering the carbonated water individually to each valve. Since carbonators 10 or 80 provide such individual delivery lines such a manifold structure is not needed. It can also be appreciated by those of skill in the art that various modifications can be made to the present invention without exceeding the scope and inventive concept thereof. For example, the number of alternating seams and ridges or the orientation and pattern thereof can be varied. Thus, seams 16 and their associated welds need not be along straight lines or lines at all, for that matter. The internal joining of halves 12 and 14 could be accomplished by any plurality of individual points or other welding patterns that sufficiently secure them together to provide for a tank that can safely withstand the intended operating pressures. In addition, carbonators made in accordance with the present invention need not be rectangular as depicted but could be of various shapes as defined by the perimeter thereof, provided the overall length and height thereof is substantially greater than the width thereof so that the carbonator is relatively flat or narrow in its width dimension in proportion to its length and height. Also, it can be appreciated that carbonators 10 or 80 can be located in different positions and orientations within a water bath or ice bin of a beverage dispensing device, and, of course, can be used externally of a beverage dispensing device. For example, carbonator 80 could be oriented substantially horizontally at a shallow angle at the bottom of dispenser bin 72 above or below plate 71. The shallow angle would provide for a space at "top" end 29 so that a pressure head gas space could be maintained. Of course, any level sensor used therein may have to be modified to account for the changed high and low water sensing operation that would be occasioned by such a substantially horizontal orientation.
A further embodiment of the carbonator of the present invention is seen in FIGS. 12, 13 and 14, and generally referred to by the numeral 120. Carbonator 120 is basically the same as carbonator 10 with the exception that it has two structural improvements that provide for increased resistance to failure in high pressure applications. Carbonator 120 has a perimeter seam 121, front and rear sides 122 and 123, and includes five carbonated water delivery lines 124, a plain water inlet line 126 and a carbon dioxide gas inlet line 128. Carbonator 120 also has the same "washboard" structure of alternating valleys 129 and ridges 130, such that when welded together, form upper and lower tank volumes 132 and 134 and a plurality of vertical tank columns 136. In particular, perimeter seam 121 is formed by the welding of overlapping edges 138 and 140 of sides 122 and 123.
It can be seen that lines 124, 126 and 128 extend laterally from rear side 123 from upper and lower tank volumes 132 and 133. This structure is in contrast to what is seen in the previously described carbonators wherein the counterpart inlet and delivery lines thereof exit directly from the perimeter rims thereof. Such securing of lines 124, 126 and 128 is easier, from a manufacturing point of view, than forming such connections in a welded seam, and are less likely to fail or leak due to pressure. In addition, the overlap of seam 121 provides for greater strength. As with the previous carbonators disclosed herein, corresponding valleys 129 of carbonator 120 can be welded together using resistance welding, whereas the welding of seam 121 is preferably done using TIG welding. Also, as is known in the art, a post welding heat annealing process can serve to further insure against pressure failures of carbonator 120.
Claims
  • 1. A beverage dispenser comprising:
  • a plurality of dispensing valves supported along a front end of the dispenser,
  • a water bath tank, the water tank having an interior volume defined by a bottom surface and a generally vertical perimeter wall surface extending around and upward from the bottom surface, the tank for holding a volume of water and containing an evaporator coil within the water, the evaporator coil connected to refrigeration means for cooling the evaporator coil for forming an ice bank thereon, and
  • a carbonator retained in the water tank along a front portion of the perimeter wall surface adjacent the dispenser front end, for providing carbonated water to the valves, the carbonator being substantially flat and having a front surface, a back surface and a perimeter edge defining a width thereof, wherein the carbonator front surface faces and lies adjacent the front portion of the perimeter wall surface.
  • 2. The dispenser as defined in claim 1, and further including a plurality of syrup lines for delivering syrup from sources thereof to the valves and the syrup lines each having a coil portion in the tank, each coil portion representing a majority of the length of each syrup line and the syrup line coil portions lying closely adjacent and along the carbonator back surface.
  • 3. The dispenser as defined in claim 2, and further including an agitator motor having a shaft extending into the water below a top surface thereof, the shaft having an agitating blade on an end thereof for agitating the water, and the shaft extending at an angle relative to the water top surface for directing a flow of water in a direction at least partially towards the perimeter wall surface front portion and towards the tank bottom surface, and the tank bottom surface having a linear ridge extending therefrom substantially parallel to the perimeter wall surface front portion and positioned between the agitating blade and the syrup line coil portions for deflecting the flow of water created by the agitating blade during operation of the agitator motor upward from the bottom surface towards the syrup line coil portions and the carbonator.
  • 4. The dispenser as defined in claim 3, and the linear ridge also serving to retain the syrup line coil portions adjacent the carbonator.
  • 5. The dispenser as defined in claim 3, and the evaporator coil positioned substantially centrally in the tank and defining a central open area around which the evaporator coil extends and into which open area the agitator shaft and blade extend and the evaporator coil positioned in the tank so that a bottom surface of the ice bank forms closely adjacent the tank bottom surface around a U-shaped bottom perimeter portion of the central open area and wherein a bottom portion of the ice bank adjacent and coextensive with the carbonator does not form closely adjacent the tank bottom surface, and the tank bottom surface having a U-shaped ridge extending therefrom and coextensive with the U-shaped bottom perimeter portion of the central open area for directing any secondary flow of water created by the agitator blade in the direction of the U-shaped bottom perimeter portion of the central open area away therefrom.
  • 6. The dispenser as defined in claim 1, and the evaporator coil positioned substantially centrally in the tank and defining a central open area around which the evaporator coil extends and into which open area an agitator shaft and blade extend and the evaporator coil positioned in the tank so that a bottom surface of the ice bank forms closely adjacent the tank bottom surface around a U-shaped bottom perimeter portion of the central open area and wherein a bottom portion of the ice bank adjacent and coextensive with the carbonator does not form closely adjacent the tank bottom surface, and the tank bottom surface having a U-shaped ridge extending therefrom and coextensive with the U-shaped bottom perimeter portion of the central open area for directing any secondary flow of water created by the agitator blade in the direction of the U-shaped bottom perimeter portion of the central open area away therefrom.
Parent Case Info

The present application is a co-pending continuation-in-part of U.S. patent application Ser. No. 07/936,153, filed Aug. 26, 1992, still pending.

US Referenced Citations (10)
Number Name Date Kind
3056273 Cornelius Oct 1962
3892335 Schroeder Jul 1975
3926342 Selvia et al. Dec 1975
4497179 Iwans Feb 1985
4615466 Credle, Jr. Oct 1986
4781310 Credle, Jr. et al. Nov 1988
4916910 Schroeder Apr 1990
4940164 Hancock et al. Jul 1990
5190188 Credle, Jr. Mar 1993
5234131 Griffin Aug 1993
Continuation in Parts (1)
Number Date Country
Parent 936153 Aug 1992