Abstract:
A collar assembly including cooling coils is provided to increase the top surface cooling of food being served from food pans which are mounted to extend down into a food service cabinet or counter. The collar is preferably lower in the front toward the server or may be omitted for easy access, and is preferably higher at the back away from the server and on the sides for increased cooling. A principal cooling unit may be mounted in the cabinet to direct cold air onto the food pans; and the collar cooling coils and the principal cooling unit may be coupled to a single compressor and heat exchanger.

Description:
RELATED PATENT APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 10/033,600, filed, Dec. 27, 2001 entitled “Cool Wrap Food Service Refrigeration System”. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to refrigeration arrangements for increasing the cooling at the upper surface of food which is being served from food pans on a counter or cabinet. 
     FIELD OF THE INVENTION 
     It has previously been proposed to provide arrangements for increasing the upper surface cooling of food in food pans, and certain prior arrangements directed to this goal are disclosed in the following U.S. Patents: 
     U.S. Pat. No. 4,685,311 Granted: Aug. 11, 1987 
     Title: Food Preparation Table Having A Refrigerated Ingredient Zone 
     U.S. Pat. No. 5,168,79 Granted: Dec. 8, 1992 
     Title: Food Preparation Table With Open Air Food Storage 
     U.S. Pat. No. 5,381,672 Granted: Jan. 17, 1995 
     Title: Cabinet Refrigeration System with Cold Air Distributor 
     U.S. Pat. No. 5,927,092 Granted: Jul. 27, 1999 
     Food Pan Refrigeration Unit 
     U.S. Pat. No. 6,089,036 Granted: Jul. 18, 2000 
     Title: Open-Top Chilling Apparatus 
     However, in some cases the proposed arrangements involve the flow of air over the food, and this air flow may impair the quality of the food being dispensed. Also, in some cases the food pans may be so recessed down into the food service counter or table, as to be inconvenient for the server to access the food. Further, there are many existing installations where the food pans have an upper lip which is substantially at the level of the serving counter or table; and these older installations may not adequately protect the food against spoilage resulting from the exposed upper surface of the food. 
     SUMMARY OF THE INVENTION 
     In accordance with one illustrative embodiment of the invention, a cooling collar or wrap is provided which may be retrofitted onto existing food pan service counters or tables. The collar or wrap may contain cooling coils, and may be coupled to the existing cooling system having the usual compressor and heat exchanger. The cooling collar or wrap is preferably somewhat lower or may be omitted at the front toward the server, for easy access, and may be somewhat higher at the back away from the server to provide additional cooling. By way of example and not of limitation, the height at the front of the collar toward the server may be about one to three inches, and the height at the back, away from the server may be about three to six or seven inches. Also, as noted above, the cooling collar may be open toward the server, and have only three sides with one side extending along the food pans on the side away from the server and also extending at least part way along the two ends of the installation. Alternatively, in order to provide better visibility for the customer, the collars may be the same height in the front and back, or may even be slightly lower in the front than the back. 
     Additional features may include an inner stainless steel liner and an outer metallic housing or shell, with the coils engaging the inner liner, and foamed-in-place insulation between the inner liner and the outer housing. The upper edges of the inner liner and outer housing may be separated by a thermally insulating strip. While the unit is particularly suitable for retrofit applications, initial complete installations may also be designed with substantially the same resultant configuration. 
     In accordance with another aspect of the invention, a food service cabinet may be provided with pans extending down into the cabinet, and a first cooling unit within the cabinet directing cooling fluid to cool the pans; and an additional upper cooling collar may be provided, with the collar configuration including constructional features as suggested hereinabove; and the two cooling arrangements may be coupled to a single compressor and heat exchanger. 
     Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and from the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a refrigeration system illustrating the principles of the invention; 
     FIG. 2 is a schematic view of the refrigeration components of the system; 
     FIG. 3 is a schematic cross-sectional view of the pan installation; 
     FIG. 4 is an enlarged cross-sectional view of the collar shown in FIGS. 1 and 3; and 
     FIG. 5 shows an open collar refrigeration arrangement in which the cooling collar extends around three sides of the food service. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to the drawings, FIG. 1 shows a refrigeration counter or cabinet  12  with an inner refrigeration unit  14  for directing cold air onto the lower surfaces of the food pans  16  which are recessed into the surface of the refrigeration cabinet  12 . The refrigeration unit  14  may also cool the inside of cabinet  12  for food storage or the like. 
     A cooling collar  18  is mounted to extend around the upper surfaces of the food pans  16  to provide surface cooling. As shown in FIG. 1, the front  20  of the cabinet may be lower than the rear side  22  of the refrigeration system, for access by the server and to provide as much as cooling as is reasonably practical in view of the desire to have customers be able to see into the food pans and observe the food which is available. The principal cooling unit  14  may be mounted on the rear wall of cabinet  12 , and includes arrangements  24  for directing cold air up toward the cooling pans  16 . It is also noted that the principal cooling unit  14  may be of the configuration shown in my prior U.S. Pat. No. 5,381,672, and the disclosure of that patent is hereby incorporated into the present patent application by reference. 
     Referring now to FIG. 2 of the drawings, it shows the complete refrigeration system including the principal cooling unit  14  with a baffle  24  for directing cold air upward toward the bottom of the food pans  16 . In addition, the system of FIG. 2 includes the rear coils  26  and the front coils  28  associated with the collar  18  as shown in FIGS. 1 and 3 of the drawings. Also shown in FIG. 2 is a heat exchanger or cooling tower  30  and a compressor  32 . The cooling tower or heat exchanger  30  and the compressor  32  are normally located outside of the building which the refrigeration unit or cabinet is located. In accordance with normal refrigeration practice, Freon™ or other similar refrigerant is returned to the compressor  32  where it is compressed and heated somewhat and routed to the heat exchanger or cooling tower  30  where it is liquefied, as its temperature is further reduced. Then the refrigerant is routed to an expansion valve (not shown), and the resultant cold refrigeration gas is directed to the refrigeration coils  26  and  28 , as well as to similar refrigeration coils within the principal refrigeration unit  14 . 
     Referring now to FIG. 3 of the drawings, a schematic cross-sectional view of the cabinet  12  of FIG. 1 is shown, with the cooling collar  18  being shown separated from the cabinet in order to emphasize that the collar  68  may be provided as a retrofit to existing food service counters or cabinets, or may be built as an integral part of the refrigeration system. 
     Referring now to FIG. 4 of the drawings, it is a cross sectional view through the wall  22  of the refrigeration collar,  18 . The inner wall  42  of the collar  18  is preferably formed of stainless steel. In addition, Z-shaped supports  44  are mounted on the stainless steel wall  42  using spot welds, rivets, glue, or any other suitable technique. In addition, thermal mastic  46  is located around the cooling tubes  26  to ensure good heat transfer from the cooling coils to the inner wall  42  of the cooling collar. Thermal mastic is widely available from a number of sources but may for example, be purchased from Component Hardware having an address at 4560 Loma Vista Ave., Los Angeles, Calif. 90058. Following assembly of the cooling tubes within the chamber formed by the inner wall  42  and the outer wall  48 , a foamed-in-place thermal insulating material is provided. It is applied through an opening in the outer wall  48  through a gun which combines two parts and injects the resultant material as a foam through the outer wall. The chemical name for the foam material is methane chlorodifluoro. Foam thermal insulating material is available from various sources, one of which is Foam Supply, Inc., having an address at 4387 North Rider Trail, Earth City, Mo. 63045. The foamed in place material is identified by reference numeral  52  in FIG. 4. A food pan  16  shown in dash lines in FIG. 4 has an outwardly extending lip  56  which rests on a L-shaped support member  58  which is mounted on the wall  60  on the main part of the food service cabinet or counter  12 . The support member  58  may be continuous around the rim of the food pan or may be in the form of a series of spaced brackets. 
     With reference to FIG. 4 of the drawings, attention is directed to the thermal breaker strip  64  made of a strip of low thermal conductivity insulating material, and to the upper stainless steel closure member  66 . In the absence of the breaker strip  64 , the top cover plate  66  could become unduly cold, and undesired moisture would condense on the surface thereof. 
     Referring now to FIG. 5 of the drawings, this embodiment includes an open collar construction in which the cabinet  72  has food pans  74  and an open front cooling collar  76 . The cooling collar  76  includes the extended side  78  on the side of the installation away from the server, and the two end portions  80  and  82  extending at least partially along the ends of the linear array of food pans  74 . As in the case of the other installations described hereinabove, the cooling coils  86  may be mounted within the cooling walls  78 ,  80  and  82 . 
     It may also be noted that the inner cooling unit  14 ′ and the deflector  24 ′ are also visible in FIG. 5; and the FIG. 5 system may be cooled in accordance with the system shown in FIG. 2 of the drawings. 
     In the foregoing detail and description, illustrative preferred embodiments of the invention have been disclosed. However, various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, by way of example and not of limitation, the cooling collar may be either a separate unit available for retrofitting onto existing food service refrigeration units, or may be integrally built into food service cabinets. Concerning the thermal mastic, any material having high thermal conductivity properties may be employed, and even without the thermal mastic, good heat conduction is provided by engagement of the coils  26  with the wall  42 , and by the supplemental heat or cooling conduction properties of the Z-shaped bracket members  44 . Instead of the foamed-in-place thermal insulation  52 , preformed slabs of thermal insulation material may be employed. Other high heat conductivity material may be employed instead of stainless steel. Concerning the height of the collar, the front of the unit toward the server is preferably about two inches or one to three inches in height, or the front portion may be omitted, and the height of the rear wall  22  is preferably about 4 inches; and it may be, for example, from 2 to 7 inches in height in accordance with the nature of the facility and the appropriate design parameters. The main cooling arrangements for the food pans may be a separate unit mounted within the cabinet as shown, or may involve additional coils extending around the food pans  16 , within the cabinet, either with or without the additional main cooling unit  14 . Accordingly, the present invention is not limited the specific design shown in the drawings and described in detail hereinabove.