US3531945A - Constant temperature refrigerated equipment - Google Patents

Description

Oct. 6, 1970 J. H. BRENNAN 3,531,945

CONSTANT TEMPERATURE REFRIGERATED EQUIPMENT Filed June 11, 1969 3 Sheets-Sheet 1 Jnue's H. bmalwm BY w A TORHEYS J. BRENNAN 3 Sheets-Sheet 2 Filed June 11, 1969 lHVEHTOR JAMEs H. BRENNAN ATTORNEY;

Oct. 6, 1970 J. H. BRENNAN 3,531,945

CONSTANT TEMPERATURE REFRIGERATED EQUIPMENT Filed June 11, 1969 Sheets-Sheet 5 I NVENTOH. JAME5 H. bIiEHMHU RTTO RUBY! United States Patent 3,531,945 CONSTANT TEMPERATURE REFRIGERATED EQUIPMENT James H. Brennan, Trenton, N.J., assignor to Emhart Corporation, Bloomfield, Conn, a corporation of Connecticut Continuation-impart of application Ser. No. 693,200, Dec.

26, 1967, which is a continuation-in-part of applications Ser. No. 608,340, Jan. 10, 1967, and Ser. No. 621,909, Mar. 9, 1967. This application June 11, 1969, Ser. No. 832,328

Int. Cl. Fd 21/00 US. Cl. 62-234 7 Claims ABSTRACT OF THE DISCLOSURE Refrigerated equipment is provided with a plurality of refrigerating units which are alternately operated on refrigerating and defrosting cycles with the units receiving air from a common return air plenum chamber and discharging refrigerated air to a common refrigerated air plenum chamber and into heat exchanging relation with space within the equipment. Dampers are operable to preclude the circulation of air from the return air plenum chamber to the refrigerated air plenum chamber through those units operating on a defrosting cycle while permitting air to be circulated through those units operating on a refrigerating cycle.

RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 693,200 filed Dec. 26, 1967, which in turn is a continuation-in-part of abandoned application Ser. No. 608,340 filed Ian. 10, 1967, and abandoned application Ser. No. 621,909 filed Mar. 9, 1967.

FIELD OF INVENTION It is usual practice to provide refrigerated equipment with one or more evaporator units over which air circulated to refrigerate a chamber. However, the accumulation of ice and frost on the evaporators renders it necessary to defrost the evaporators from time to time by circulating hot refrigerant gas or liquid through the evaporators or by utilizing electrical heating elements for raising the temperature of the evaporators above freezing to melt such ice. In some systems, the circulation of air over the evaporators is discontinued during the defrosting operation while other systems continue the circulation of air to speed up the defrosting operation. In either method, the temperature of the air within the refrigerated equipment will rise and, as a result, the condition of the products may be impaired and moisture may collect on the products and walls or ducts in the equipment where it is refrozen into ice when the refrigeration cycle is renewed. Food packages then may be frozen together so as to render it difficult to remove them from the equipment and ice may accumulate on the walls and other surfaces of the refrigerated equipment.

In accordance with the present invention, a plurality of evaporator units are provided for the equipment and these units are alternately and sequentially defrosted so that one or more units will be operating on the refrigerating cycle at all times to supply refrigerated air to the equipment. At the same time, the circulation of air over the evaporator units being defrosted is prevented by means of movable dampers so that the temperature of the air being circulated to the equipment does not rise. Further, in order to assure uniform distribution of the refrigerated air to and through duct means employed for conducting air to and from the equipment, a common return air plenum chamber is provided to which air from the equipment being refrigerated is supplied and a common refrigerated air plenum chamber is provided to which refrigerated air from the evaporators operating on a refrigerating cycle is supplied for circulation through refrigerated air ducts to the equipment to be refrigerated.

While the invention is adapted for use in maintaining a constant supply of refrigerated air at substantially uniform temperature to various type of equipment to be refrigerated, it is particularly useful in equipment employed in the preservation of meat products since such products are known to deteriorate rapidly when subjected to even limited variations in temperature. Moreover, when the equipment is of the self-service type having an access opening and means for establishing an air barrier adjacent the opening, a rise in temperature of the air forming the air barrier occurring during a defrosting operation will result in an increase in the amount of moisture taken up by the air from the ambient atmosphere and an increase in the accumulation of ice and frost on the refrigerated surfaces of the equipment. Accordingly, the present invention is particularly advantageous when used with such self-service refrigerated equipment.

THE DRAWINGS FIG. 1 is a vertical sectional view through one typical form of equipment embodying the present invention;

FIG. 2 is a diagrammatic illustration of typical refrigerating means used in the equipment of the presentinvention;

FIG. 3 is a vertical sectional view of an alternative form of refrigerated equipment embodying the present invention;

FIG. 4 is a diagrammatic front elevation of one arrangement of the evaporators employed in the equipment of the present invention;

FIG. 5 is a vertical sectional view through the upper portion of a further alternative form of equipment embodying the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION In that form of the invention chosen for purposes of illustration in FIGS. 1 and 2, the equipment embodies an insulated enclosure having a bottom 2, a rear wall 4 and a top wall 6. The front of the equipment has an upper wall portion 8 and a lower wall portion 10 which are spaced apart to provide an access opening 12 in the front of the case.

The refrigerated space 14 within the equipment has a perforated shelf or article support 16 located adjacent and below the access opening 12 to provide a display area 18 whereas the rear wall of the refrigerated space 14 is spaced from the display area by an aisle which constitutes a services area 20 located at the rear of the display area. The service area is in continuous and open communication With the display area to enable service personnel to wait upon customers and maintain the supply and arrangement of the articles in the display area in a well stocked and attractive arrangement at all times.

An air barrier 22 is establihed adjacent the access opening by directing air downward through a discharge outlet 24 located adjacent the upper edge of the access opening and extending substantially the full width of said opening. The air forming the air barrier 22 is drawn into an inlet opening 26 located adjacent the lower edge of the access opening and through an air passage 28 by means of a blower 30. The blower serves to direct such air rearwardly through the service area 20 toward a return air inlet 32 located at the rear of the refrigerated space 14 and preferably located below the perforated shelf 16 in the display area.

Additional refrigerated air is caused to flow downward through the refrigerated space 14 and the display and service areas thereof by passage through additional air outlets 34 in a ceiling panel 36 which extends across the top of the refrigerated space at a level above the access opening 12. A lighting fixture 38 may also be mounted on the ceiling panel 36 if desired. A portion of the air issuing from the additional air outlets 34 flows downward adjacent the air barrier 22 and serves to support the air barrier so as to prevent it from being deflected inwardly in a manner to permit the entry of warm moist ambient air into the refrigerated space. This portion of the additional air also serves to cool the display area and maintain the articles on display on the perforated shelf 16 at a desired low temperature. The air then flows rearwardly from the display area and through the lower portion of the service area 20 to the return air inlet 32 at the rear of the service area. The remainder of the air from the additional air outlets 34 flows downward through the refrigerated space 14 and the service area 20 thereof to cool the same. This air then also flows rearwardly to the return air inlet 32.

The return air inlet 32 preferably extends the full width of the refrigerated space and communicates with a return air duct formed by a heat transmitting panel 42 spaced from the insulated rear wall 4 of the equipment. The upper end of the return air duct communicates with a return air plenum chamber 44 through which air is directed by the blowers 46 into heat exchanging relation with refrigerated means 48. The air cooled by the refrigerating means 48 then flows forward into an air discharge plenum chamber 50 and into an additional air plenum chamber 52. The air from the air discharge plenum chamber 50 flows through a discharge duct 54 of reduced cross section to the air discharge outlet 24 whereby its velocity is increased and it is directed downward across the access opening to establish the air barrier 22. At the same time the air from the additional air plenum chamber 52 is caused to flow downward through the additional air outlets 34 adjacent the inner side of the air barrier 22 and into and through the refrigerated space 12.

In order to maintain the temperature within the refrigerated space substantially constant and assure the preservation of the articles on display at a substantially uniform temperature, the refrigerating means 48 preferably embodies a plurality of refrigerating elements indicated at 5,6, 58, and 62 in FIG. 2. Each refrigerating element is provided with one or more blowers 46 for directing air from the return air plenum chamber 44 over the refrigerating element to the discharge plenum chamber 50 and the additional air plenum chamber 52. However, each element also is provided with an enclosure 66 having dampers or other closure members 68 and 70 at the outlet side thereof where the closure communicates with the discharge and additional air plenum chambers 50 and 52. The closures 68 and 70 are movable by gravity or otherwise to closed positions so as to prevent the passage of warm air into the plenum chambers 50 and 52 when any refrigeration element is being defrosted. All of the air supplied to the plenum chambers 50 and 52 is therefore refrigerated air cooled by those element which are being actively refrigerated whereby the air delivered to the air discharge outlet 24 and to the additional air outlets 34 will always be maintained at a constant and predetermined low temperature.

In the refrigerating system shown in FIG. 2 the refrigerating means 48 embodies the four refrigerating elements 56, 58, 60 and 62 which are supplied with refrigerant from a compressor 72, condenser 74 and receiver 76 through a refrigerant supply line 78. Each refrigerant element is, of course, provided with an expansion valve 80 and is connected to a refrigerant return line 81 leading back to compressor 72.

The various refrigerating elements are arranged to be successively defrosted under control of time clocks or other suitable means 84 which are connected into the power supply lines 86 and electrical circuits 88 in such a way as to render the blowers 4-6 associated with the element being defrosted inactive during the defrosting cycle of operation. The dampers or closure members 68 and 70 at the outlet side of the enclosure 66 for the element being defrosted are thereby closed during the defrosting period and the heat utilized in defrosting such element does not cause the temperature of the air delivered to the discharge and additional air plenum chambers 50 and 52 to be raised.

In the construction shown in FIG. 2 the defrosting of the refrigerating elements is effected by means of hot refrigerant gas received from the compressor 72 through the by-pass line 90 upon actuation of the three-way valves 92 under control of the time clocks 84. Refrigerant condensed in the evaporators being defrosted is returned to the receiver 76 through return line 82. Further as shown the refrigerating elements 56, 58, 60 and 62 may be arranged in pairs so that two elements, such as the elements 56 and 60, may be defrosted while the two remaining elements 58 and 62, continue to remain on the refrigerating cycle of operation under control of thermostat 85. As a result of the plenum chambers 50 and 52 are continually supplied with cool refrigerated air from at least two of the refrigerating elements whereby the temperature of the air which is discharged through the discharge outlet 24 to establish the air barrier 22 and through the additional air outlets 34 to cool the display and service areas of the refrigerated space 14 is maintained substantially uniform under all conditions of operation of the equipment.

In that form of the equipment illustrated in FIG. 3 of the drawings the air barrier 116 adjacent the access opening 12 in the front of the case embodies two opposed streams of air 112 and 114 which are directed into impinging contact and thereafter combine and flow inwardly through the refrigerated space 24 to the return air inlet 32 near the rear of the service area 20. In this construction the display area 16 is provided with an article support which may be imperforate and further, as shown, the equipment may be provided with additional shelves 102 mounted on a bracket 104 which extends upwardly at the rear of the article support 100.

Air from the service area 20 is caused to flow forwardly beneath the article support 100 by a blower 106 and is forced through the lower air duct 108 so as to issue through a second air discharge outlet 110. The air thus discharged flows upwardly to form the lower portion 114 of the air barrier 116 whereas air directed downwardly from discharge opening 14 forms the upper portion 112 of the air barrier. These streams of air combine to establish the air barrier 116 and create a pressure area adjacent the mid-area of the access opening opposing the entry of air into the refrigerated space and decreasing the tendency for the air barrier to be deflected inwardly toward said space.

The construction shown in FIG. 3 also has the additional air outlets 34 confined to the forward portion of the ceiling panel 36 and communicating with the addi-' tional air plenum chamber 52. Additional blower means 118 may also be used to promote the flow of air downward through the additional air outlets 34 and parallel to the upper portion 112 of the air barrier 116 and also serves to assure the desired uniform cooling of the articles on display in the display area 18 and on the support 100 and shelves 102. In this way a larger volume of articles may be presented for cooling and access to the customers whereas the proper cooling or refrigeration thereof is assured.

The air from both the upwardly directed stream 114 and the downwardly directed stream 112 which combine to establish the air barrier 116, flows inwardly through the refrigerated space 14 and into the service area 20.

A portion of such air is withdrawn from the service area by the blower 106 for recirculation in forming the lower portion 114 of the air barrier whereas the major portion of such air is drawn off through return air inlet 32 and return air duct 40 for recirculation and cooling by the refrigerating means 48. In this way the refrigerated space 20 is maintained at an even more uniform and predetermined temperature while the entrainment and entry of ambient air into the refrigerated space is reduced and the spillage of cold air and the loss of refrigeration is minimized.

The refrigerating system employed in cooling the air when using the equipment of FIG. 3 is preferably similar to that illustrated in FIG. 2 in that the air utilized in establishing the air barrier 116 and in cooling the refrigerated space 114 does not undergo any rise in temperature during the defrosting periods of the refrigerating elements embodied in the refrigerating system.

However, the equipment is further provided with an outer guard air circuit by which a guard layer of air is projected downward on the outer side of the upper portion 112 of the air barrier 11-6 established adjacent the access opening 12. For this purpose the equipment is provided with a guard air duct 120' located between the rear wall 4 and the refrigerated air duct 40 and has an inlet air opening at 122 below the return inlet air opening 32 of the refrigerated air duct. The guard air duct 120 extends upwardly and forwardly beneath the insulated top 6 of the equipment and terminates in a downwardly extending discharge passage 124 positioned between the upper front wall portion 8 of the equipment and the refrigerated air discharge duct 54. The discharge passage 124 of the guard air duct has a discharge opening 126 positioned adjacent the discharge outlet 24, of the refrigerated air discharge duct at the upper edge of the access opening 12. The guard air duct 120 is preferably maintained in heat exchanging relation with the return air duct 40 and the plenum chambers 44 and 50 throughout the length thereof and air is forced through the guard air duct by means of one or more blowers 128.

In this way, a guard panel of air 130 is established on the outer side of the upper portion 112 of the air panel 116. This air has an initial temperature upon entering the inlet opening 122 at the rear of the service area 20 corresponding to that of the air in the refrigerated space 14 and is maintained at a temperature higher than the temperature of the air forming the upper portion 112 of the air barrier 116 but somewhat lower than the temperature of the ambient air in front of the access opening 12. At the same time the guard panel of air 130 becomes a part of the air barrier and provides an outer support for the refrigerated stream air preventing outward diffusion thereof into the ambient air. While the refrigerated air issuing from the additional air outlets 34 in ceiling panel 36 supports the upper portion 112 of the air barrier on the inner side thereof so as to minimize diffusion and turbulence in the air barrier adjacent the upper portion 112 thereof. The guard air 130 also cooperates with the upwardly projected lower portion 114 of the air barrier so as to prevent the spillage of refrigerated air over the lower front wall of the case. As a result the loss of refrigerated air and the load on the refrigerating means is reduced.

The downwardly flowing guard panel of air 130 upon contacting the lower and upwardly or inwardly projected air stream 114 is deflected inwardly and over the articles on the shelves 102 and merges with the refrigerated air from the upper air stream 112. The air streams then flow inwardly and downwardly and through the refrigerated space 14 to the return air inlet 32 and the inlet opening 122 of the guard air duct 120.

Furthermore, the blower or blowers 128 which serve to circulate the guard air are preferably operated continuously and independently of any defrosting cycle. The guard air thus serves to reduce fluctuations in the temperature maintained within the refrigerated space and about the articles on the shelves 102 during those periods when one or more of the refrigerating elements 56, 58, 60 and 62 is being defrosted and the supply therefrom is terminated. This result is attained by reason of the fact that only a portion of the relatively large volume of air forming the air barrier and circulating through the refrigerated space 14 is cut off during the successive defrosting cycle of any one or more of the refrigerating elements. Moreover the defrosting period and the reduction in supply of refrigerated air to the equipment is in any event of relatively short duration and the over-all temperature rise of the air during such period is minimal.

In order to assure substantially uniform distribution of the refrigerated air forming the air curtain 22 throughout the length of the refrigerated air plenum chamber 50 for passagfe to the discharge outlets 24, the evaporators which serve as refrigerating elements may be arranged in pairs one above the other as represented at a and 142a; 140k and 1421); etc., in FIG. 4. One or more of the evaporators of the pair is refrigerating. Thus, as indicated by the cross-hatching in FIG. 4, the evaporators 140a and 142b may be defrosting and have the flow of air thereover cut off while the evaporators 1401: and 142a are refrigerated and serve to supply refrigerated air to the refrigerated air plenum chamber. In such an arrangement, refrigerated air will be supplied to the refrigerated air plenum chamber 50 at all points throughout the length thereof. While the supply of refrigerated air will be reduced in those areas corresponding to the cross-hatched evaporators, the other refrigerating units will continue to supply refrigerated air and the supply of the cold air will not be wholly cut off at any point throughout the length of the equipment. With this arrangement of the evaporators substantially uniform, temperature conditions can be maintained throughout the length of equipment extending the full length or along one whole side of a store or market if desired.

The present invention is nevertheless adapted for use in shorter and more conventional types of refrigerated display cases as illustrated in FIG. 5 wherein the upper portion of display case is shown. This construction is adapted for use with equipment which may or may not be provided with a service area at the rear of a display area in the refrigerated space.

As shown in FIG. 5, the refrigerated space of the equipment is provided with a ceiling 152 above which the refrigerating elements, one of which is shown at 154, are located. A common return air plenum chamber 156 receives air from a return air duct 158 whereas air is drawn over the refrigerating element 154 to the refrigerated air plenum chamber 160 by a blower 162. Air thus refrigerated is discharged from the refrigerated air plenum chamber through the refrigerated air duct 164 to the discharge opening 166 arranged to direct a layer of refrigerated air downwardly from adjacent the upper edge of the access opening 168 in the front of the refrigerated space 150. If desired, some of the air from the refrigerated air plenum chamber 160 may also be caused to circulate through the refrigerated space 150 by providing additional air outlet openings 170 in the ceiling 152 of the refrigerated space.

In order to provide a more effective air barrier adjacent the access opening 168, air from the return air plenum chamber 156 is forced through a secondary air duct 172 by a blower 174 and is directed downwardly through the discharge opening 176. The opening 176 is located adjacent and on the outer side of the discharge opening 166 of the refrigerated air duct 164,.so as to provide a guard layer of air 178 on the outer side of the refrigerated or primary layer of air 180 of the air curtain established in the access opening 168 to the refrigerated space 150.

The refrigerating elements employed are designed to be I alternately and successively operated on refrigerating and defrost cycles as described in connection with FIG. 2.

For this purpose a damper 182 is located between the evaporator 154 and the refrigerated air plenum chamber 160. The damper 182 is movable from the full line position of FIG. 5 to the dotted line position shown, so as to be operable to prevent the flow of air over the refrigerating unit when it is in the full line position and the evaporator is being defrosted While allowing free flow of air over the unit when in the dotted line position and the evaporator is operating on the refrigerating cycle.

Further, in order to render the fiow of air to the refrigerated air plenum chamber 160' more nearly uniform at all times, a passage 184 is provided which by-passes the refrigerating unit 154. The passage 184 communicates at one end with the return air plenum chamber 156 through inlet 186 and communicates wit-h the refrigerated air plenum chamber 160 through an outlet 188. The outlet 188 is positioned so as to be closed by the damper 182 when the refrigerating element is being refrigerated and the damper is in the dotted line position of FIG. 5. In this way, at least a limited supply of air from the return air plenum chamber will be allowed to by-pass the refrigerating element when the latter is defrosting and the flow of air therethrough is cut off by the damper 182. On the other hand, all of the air passing from the return air plenum chamber to the refrigerated air plenum chamber will pass through the refrigerating unit when the latter is operating on its refrigerating cycle.

While the refrigerating system shown in 'FIG. 2 and described above utilizes hot refrigerant gas for defrosting the refrigerating units, the units may be defrosted by energizing electrical heating elements as indicated at 190 in FIG. 5 or by any other suitable means as desired. Further, whereas the dampers which are movable to control the flow of air through the refrigerating elements may be gravity actuated, it is generally preferable to operate the dampers positively by means of a motor or the like.

I claim:

1. A continuously refrigerated food merchandising structure comprising an enclosure having a refrigerated space therein with an access opening in the front thereof, a plurality of refrigerating units of the type in which refrigerating cycles alternate with defrost cycles, a refrigerated air plenum chamber common to all of said refrigerating units for receiving the outflow of refrigerated air from all of said units, refrigerated air duct means communicating with said refrigerated air plenum chamber and provided with an air discharge opening located adjacent the upper edge of said access opening, closure means associated with each of said refrigerating units movable to a closed position during the defrost cycles of the associated unit to prevent flow of air to said refrigerated air plenum chamber from the unit during the defrost cycle thereof, said closure means being movable to an open position during the refrigerating cycles of the associated unit, a return air plenum chamber common to all of said refrigerating units, return air duct means communicating with said refrigerated space and with said return air plenum chamber, a further air duct communicating with said refrigerated space and having a discharge opening located adjacent the upper side of the access opening and in position to direct a layer of return air downwardly on the outer side of the layer of refrigerated air discharged from the discharge opening of said refrigerated air duct means and blower means for circulating return air from said refrigerated space through both said return air plenum chamber and said further air duct to the respective discharge opening thereof.

2. A refrigerated food merchandising structure as in claim 1 further including an additional refrigerated air duct common to all of said refrigerating units, said additional refrigerated air duct having an outlet disposed for directing refrigerated air into said refrigerated space, the closure means of each of said units including a second closure movable to open and closed position and disposed between its associated unit and said additional refrigerated air duct.

3. A refrigerated food merchandising structure as in claim 1 wherein said first and second closures of each closure means are dampers movable by gravity to their closed positions and shifting to open positions under the pressure of air forced by said blower means through their associated units, said blower means being electrically connected to the units to effect the movement of air through each unit only during the cooling cycle thereof.

4. A refrigerated food merchandising structure as defined in claim 1 wherein said further air duct communicates directly with said return air plenum chamber to receive air therefrom.

5. Refrigerated equipment as defined in claim 1 wherein there is a passage extending from the return air plenum chamber to the refrigerated air plenum chamber so as to by-pass the enclosure in which a refrigerating element being defrosted is located.

6. Refrigerated equipment as defined in claim 5 wherein a damper is movable to open said by-pass passage when the refrigerating element is being defrosted and is movable to close the by-pass passage when the refrigerating element is operating on a refrigerating cycle.

7. Refrigerated equipment as defined in claim 1 wherein there is a secondary air duct communicating with said inlet plenum chamber and having a discharge opening positioned to direct a stream of air downward adjacent and on the outer side of the stream of air from the refrigerated air plenum chamber which is directed downwardly adjacent the access opening by said duct means.

References Cited UNITED STATES PATENTS 2,254,420 9/1941 Cleveland 62419 3,063,252 11/1962 Laint 62256 3,103,796 9/1963 Dickson 62234 3,115,017 12/1963 Kocher 62---234 3,257,816 6/1966 Parce 62234 WILLIAM J. WYE, Primary Examiner U.S. Cl. X.=R. 62419, 256

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