Abstract: A refrigerated display case having a configuration resulting in a restricted air flow recirculation channel, such as a wedge shape, and comprising a housing having a bottom, a top, and defining a display space and an access thereto, the housing having a lower well and at least one shelf above the well, a refrigeration coil beneath the well, an air inlet to the coil from the display space, and an air outlet from the coil, at least one fan adjacent the coil for propelling air from the air inlet, through the coil, to the air outlet, an air flow opening from the outlet the well, the display case having a configuration forming a restricted vertical air flow channel from the outlet up the case to the top, an air discharge opening from the channel down toward the air inlet to the coil, and at least one fan in the channel adjacent the top for drawing air up the channel and discharging the air through the discharge opening.

Abstract: A refrigerated display case having an upper display space for food products at a temperature above freezing, and a lower wall display space for food products at a temperature below freezing, a single set of refrigeration coils adjacent said well, with refrigerated air propelled from said coils during the refrigeration cycle to both the upper and lower spaces, including across the open top of the lower space, and through the upper space between its shelves and its front doors, and with warmed defrost air during the defrost cycle flowing through the coils and circulated only around the lower space while air in the upper space remains substantially dormant.

Abstract: A refrigeration system for a display case including electronic means for controlling an expansion valve and a refrigerant compressor used in the system. The expansion valve is cycled between open and close positions to modulate refrigerant flow into an evaporator coil. A microprocessor controls the operation of the expansion valve in response to: (a) the relationship of the temperature of air that has passed over the evaporator coil to multiple upper and lower limits (b) time integrated temperature deviations beyond preselected limits (c) upward or downward trend of the differential in temperature in the refrigerant during its flow through the evaporator coil, and (d) extreme deviation of the temperature of air that has passed over the evaporator coil. Compressor cut-in and cut-out pressures are also adjusted by the control in response to these air and refrigerant temperatures.

Abstract: An improved evaporator unit in which a cooling tube core is placed between guide panels which permit a portion of the refrigerated air band to by-pass the front air opening of the core and to thereafter be forced into the core along a substantial longitudinal length of one or more side air openings. The flow of an auxilliary portion of the air stream into the side air opening permits the diffusion of frost build-up within the cooling tube core. A heater is provided for use during a defrost cycle in order to add heat directly into the cooling tube core. The improved evaporator is designed for use with reverse flow air defrost refrigerated container apparatus. Use of the evaporator permits improved refrigeration and defrost cycle operation.

Abstract: An improved oil return system for use with closed circuit mechanical refrigeration systems having multiple compressors. The oil return system is responsive to the flow of refrigeration gas to the individual compressors and enables an optimum flow of crank case oil to each of the multiple compressors. The system is based on the use of oil pick-up means for each of the suction lines connected between the suction manifold and each of the compressors. This pick-up means comprises a venturi tube which provides for the flow of oil through each of the suction lines responsive to the flow of refrigerant gas therethrough. The venturi tube has an outlet end positioned in a downstream orientation with respect to the flow of refrigerant gas through a surrounding suction drop sleeve.

Abstract: An automatically operated flexible barrier cover for the access openings of refrigerated display cabinets. The barrier cover limits the contact between the refrigerated air within the cabinet and the ambient air. The barrier cover can be moved over the access opening during non-customer use time periods when the retail food outlet is closed. The barrier cover can be arranged as a unitary assembly which can be manufactured and sold separately from the display cabinet as a retrofit device to effect energy savings. The flexible barrier cover can be stored in a reeled-up position or can be arranged as a folded flexible barrier which can be fanned out across the access opening. Various traction means are provided for moving the flexible barrier across the access opening.

Abstract: A refrigerated display case having an ambient air automatic defrost system and a method of operating such a case. The display case has an access opening in one wall for enabling products within the display section to be removed. The access opening can be either in the top of front wall of the display case. At least one air conduit extends in an approximately C-shaped formation around the display case. The air conduit has openings at both ends, with such openings being located on opposite sides of the access opening. Arranged within the air conduit is at least one reversible fan and a set of refrigeration coils. During a refrigeration cycle the fan circulates air through the air conduit in a first direction towards the refrigeration coils. When frost buildup within the display case has reached a certain level, the system is switched to a defrost cycle. During the defrost cycle, the fan circulates in the opposite direction through the air conduit and draws in ambient air from outside of the display case.

Abstract: A refrigeration system including a refrigeration control system for controlling the operation of the refrigeration system so as to insure that the temperature of the refrigerant discharged from the evaporator coil is above the saturation temperature. The refrigeration system includes at least one refrigerated display case having an evaporator within the primary air conduit and an expansion valve coupled to the inlet end of the evaporator coil. The control system includes: a pressure sensor arranged within the refrigerant discharge line, i.e. suction line to compressor, from the evaporator coil; a first temperature sensor arranged at the air discharge side of the evaporator coil for sensing the temperature (T.sub.1) of the air that has passed over the evaporator coil, a second temperature sensor arranged adjacent to the refrigerant discharge end of the evaporator coil for measuring the temperature (T.sub.

Abstract: A refrigerated display case having a display section within a cabinet and a movable door covering a front access opening to such display section. The door includes a frame member in which two glass members are mounted with an air space between the glass members. A refrigeration air conduit extends along the top, bottom and rear walls of the cabinet. The air conduit has an outlet opening and an inlet opening at opposing ends thereof with the openings being in alignment so that air leaving the outlet opening will be directed towards and received by the inlet opening thereby forming an air curtain across the front opening of the cabinet along the path inside the door. During a refrigeration cycle of operation of the display case, refrigerated air is circulated through the air conduit and a refrigeration mechanism arranged within the conduit so as to establish a refrigerated air band and a refrigerated air curtain across the front opening in the cabinet.

Abstract: A refrigerated display case having an ambient air automatic defrost system and a method of operating such a case. The display case has an access opening in one wall for enabling products within the display section to be removed. The access opening can be either in the top of front wall of the display case. At least one air conduit extends in an approximately C-shaped formation around the display case. The air conduit has openings at both ends, with such openings being located on opposite sides of the access opening. Arranged within the air conduit is at least one reversible fan and a set of refrigeration coils. During a refrigeration cycle the fan circulates air through the air conduit in a first direction towards the refrigeration coils. When frost buildup within the display case has reached a certain level, the system is switched to a defrost cycle. During the defrost cycle, the fan circulates in the opposite direction through the air conduit and draws in ambient air from outside of the display case.

Abstract: A refrigerated display case having a defrost means which combines the supply of hot refrigerant gas to the refrigeration coils with the supply of ambient air in order to provide defrost action during a defrost cycle. The ambient air band is taken into and propelled out of the air conduit in a manner to prevent ambient air from being forced into the product display space in order to avoid thawing of the stored refrigerated products. The defrost air is ejected away from the access opening in order to allow a cold air layer to remain on top of stored products in an open top case. In front cases, a defrost air band is established across the access opening to form a protective air curtain in order to exclude the contacting of the stored products with high temperature and moist ambient air. The ambient air band is unidirectional during the entire defrost cycle.

Abstract: A well type open top refrigerated display case has a primary air conduit extending around the cabinet and main fans for circulating air through the primary conduit and across the open top of the cabinet in the form of an air curtain. Defrost fans are mounted in the case to draw ambient air from above the refrigerated display case into an upper portion of the primary conduit at a higher pressure than the air pressure in the region of the open top. Defrost control means are provided for energizing the defrost fans at the start of a defrost cycle to propel a portion of the higher pressure ambient air out of the primary conduit through an air opening to collide with an air curtain flowing across the open top, the flow of the air curtain being thereby reversed and caused to flow over the top of and outside the display case. A further portion of ambient air is drawn downwardly by the main fans to flow through the primary conduit and assist in defrosting the coils.

Abstract: A closed circuit refrigeration system includes a compressor, a remote condenser connected to the output of the compressor, and one or more evaporators coupled within the system. A hot gas defrost system is included to rapidly obtain a high operating defrost gas pressure upon the initiation of a defrost cycle and to thereafter maintain an adequate pressure for hot gas defrosting of the evaporators. The hot gas defrost system includes a differential pressure regulated valve which closes the compressor discharge line to shunt the hot gas discharge directly into a hot gas defrost manifold. The differential valve is controlled by a defrost control means. The refrigeration system can also include a receiver tank and a by-pass conduit for shunting refrigerant liquid through the by-pass conduit rather than through the receiver tank depending upon operating conditions. A method of operating a closed circuit refrigeration system with the above features is set forth.

Abstract: An automatically operated flexible barrier cover for the access openings of refrigerated display cabinets. The barrier cover limits the contact between the refrigerated air within the cabinet and the ambient air. The barrier cover can be moved over the access opening during non-customer use time periods when the retail food outlet is closed. The barrier cover can be arranged as a unitary assembly which can be manufactured and sold separately from the display cabinet as a retrofit device to effect energy savings.The flexible barrier cover can be stored in a reeled-up position or can be arranged as a folded flexible barrier which can be fanned out across the access opening. Various traction means are provided for moving the flexible barrier across the access opening.

Abstract: A refrigerated display case having a display space and an access opening, reversible fans for circulating air through an inner air conduit and across the access opening between a first outlet and a first inlet in a refrigeration mode to establish a primary air band; a second set of fans for circulating air through a second air conduit and across the access opening adjacent to and outwardly of the inner primary air band between a second outlet and second inlet to establish a secondary air band; and defrost cycle control means for reversing the air flow direction of the primary air band during a defrost cycle while maintaining the air flow direction of the second air band continuously in the same direction during both refrigeration and defrost cycles.

Abstract: An open top refrigerated display case having mechanisms for establishing an inner refrigerated air band encircling the display portion of the case and an outer air band also encircling the display portion and being positioned outside of the inner air band. An inner air conduit passes around the side and bottom walls of the cabinet of the display case and has an outlet opening at one end of the opening in the top of the cabinet and an inlet opening at the other end of the top opening in the cabinet. A fan circulates air through this inner air conduit with the air leaving the outlet opening and being directed toward and received by the inlet opening of the conduit, thereby establishing an inner air band along with an inner air curtain across the opening in the top of the cabinet. An evaporator coil arranged within the inner air conduit serves to refrigerate the air passing along the inner air band during a refrigeration cycle of operation.

Abstract: An improvement in refrigeration assemblies for use in conjunction with cooler structures in which food products are preserved in which an assembly of unitary, modular construction is utilized to selectively provide the refrigeration of the air mass. The assembly can be air defrosted by arranging for the flow through of ambient air to defrost the evaporator coils. At the same time, the flow of ambient air can be blocked against entry into the refrigerated air mass by the use of movable baffles. Cover gates are arranged on the assembly to permit the through flow of ambient air during the defrost cycle of operation.The refrigeration assemblies can be employed for retrofitting and on an interchangeable basis for structures to be refrigerated.

Abstract: An island refrigerated display case can be constructed so as to in effect constitute to back-to-back display cases that can be arranged as a separate aisle within a supermarket. Such an island refrigerated display case has two interior display spaces separated by a partition wall with each display space having its own access opening so as to enable refrigerated products to be removed from that portion of the case. Encircling each of the interior display spaces is an associated refrigeration air conduit. Each of the refrigeration air conduits has an inlet and outlet opening positioned so as to direct air across the corresponding access opening for the interior display space. Thus during the refrigeration cycle of operation, a refrigerated air curtain is formed between the corresponding outer wall and the center partition wall so as to extend across the associated access opening. The portions of the refrigeration air conduits that extend through the partition wall can be joined so as to form a single chamber.

Abstract: A low temperature refrigerant gas heater system for warming structural parts of refrigerated display cabinets sufficiently to prevent the formation of moisture condensate. A desuperheating means is provided for an auxiliary gas flow line taken off from a primary refrigeration circuit in order to lower the temperature of a portion of the refrigerant gas flow to within the range of about 80.degree. F. to 130.degree. F. for this purpose. The auxiliary gas have pressure-temperature-enthalpy conditions located in the superheated region or the saturation envelope area of a pressure-enthalpy diagram within these temperature limits. The use of low temperature refrigerant gas in the auxiliary flow line avoids heater line warping and buckling and customer inconvenience and discomfort problems which are incurred by use of high temperature compressor refrigerant gas.

Abstract: An open top refrigerated display case having an ambient air automatic defrost system and a method of operating such a case. A single air conduit extends in a U-shaped formation along opposing side walls and the bottom wall of the display case. The air conduit has openings at both ends in the location of the upper portions of the side walls. Arranged within the air conduit is at least one reversible fan and a set of refrigeration coils. During a refrigeration cycle the fan circulates air through the air conduit in a first direction towards the refrigeration coils. When frost buildup within the display case has reached a certain level, the system is switched to a defrost cycle. During the defrost cycle, the fan circulates the air in the opposite direction through the air conduit and draws in ambient air from outside of the display case. Since such ambient air is of a higher temperature than the normally refrigerated air, it serves to defrost the system.