Abstract:
A refrigeration apparatus includes an air chiller, a storage enclosure defining a compartment, a duct system, and a valve system. The air chiller blows chilled air into the duct system. The compartment has a first and a second opening, each of which is coupled to the duct system. The valve system has valves that can be moved to route the chilled air so that it enters into the first opening and exits the second opening, or vice versa. In one implementation, the first opening is at the top of the compartment and the second opening is at the bottom of the compartment, and the valve system is controlled by a control circuit that periodically switches the valves (via an actuator) to change the direction of the chilled air. This effectively maintains a relatively uniform temperature throughout the compartment.

Description:
TECHNICAL FIELD 
       [0001]    This application relates generally to food and beverage refrigeration and more particularly, to food and beverage refrigeration systems that alter airflow to maintain uniform temperatures. 
       BACKGROUND 
       [0002]    Maintaining a relatively uniform temperature is important in any refrigeration system, but it is particularly important in the context of food and beverage refrigeration. Without proper temperature distribution, some food in a refrigerator will be too cold, resulting in unwanted freezing and some will be too warm, which raises the risk of spoilage. In most contexts, a uniform temperature is not only desirable, but is mandated by regulations. For example, depending upon the aircraft operating authority certain types of food served on passenger airlines is required to be maintained at a maximum temperature of no more than 7° C. and in some countries 4° C. 
         [0003]    Typically, pre-prepared airline food is stored in galley carts prior to serving to passengers. However, current galley cooling systems have to force air just above freezing either into the galley carts or into insulated compartments containing several galley carts just to ensure that the temperature does not exceed the required temperature in any portion of the carts. This is due to the temperature increase as the air passes through or over the galley carts to remove the heat entering the galley cart or compartment. The lower maximum temperature requirement of 4° C means that the current cold air source is less efficient resulting in the need to use more powerful and heavier systems that use more electrical power. Thus, it can be seen that there is a need for a new method and apparatus for maintaining a uniform temperature in a refrigeration system. 
       SUMMARY 
       [0004]    In accordance with the foregoing, a method and apparatus for maintaining a uniform temperature in a refrigeration system is provided. According to an embodiment of the invention, the method involves directing chilled air through a galley cart or compartment in a first direction, switching the flow of the chilled air to a second direction (substantially opposite the first direction), and periodically repeating these steps. In another embodiment, the apparatus includes an air chiller, a storage enclosure defining a compartment, a duct system, and a valve system. The air chiller blows chilled air into the duct system. The compartment has a first and a second opening, each of which is coupled to the duct system. The valve system has valves that can be moved to route the chilled air so that it enters into the first opening and exits the second opening, or vice versa. In one embodiment, the first opening is at the top of the compartment and the second opening is at the bottom of the compartment, and the valve system is controlled by a control circuit that periodically switches the valves (via an actuator) to change the direction of the chilled air. This effectively maintains a relatively uniform temperature throughout the compartment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  shows a back perspective view of a galley cart that may be used in conjunction with an embodiment of the invention. 
           [0006]      FIG. 2  shows the cart depicted in  FIG. 1  with the door open. 
           [0007]      FIG. 3  is a front elevational view of a refrigeration system configured according to an embodiment of the invention, in which the valve system is in a first configuration. 
           [0008]      FIG. 4  is a view of the refrigeration system of  FIG. 3  in which the valve system is in a second configuration. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    Referring to  FIGS. 1 and 2 , a galley cart that is used in conjunction with an embodiment is shown. The cart, generally labeled  10 , includes an enclosure  12  and castors  14  attached to the bottom of the enclosure  12 . The enclosure  12  has a front side  16  and a back side  19 . A door  20  is attached to the front side  16  by hinges  22 . The enclosure  12  has a storage compartment  24  defined by an inner surface  26  of the door  20 , a back wall  28 , a first side wall  30 , a second side wall  32 , a ceiling  34 , and a floor  36 . 
         [0010]    Protruding from the first and second side walls  30  and  32 , are rails  38 , which are configured to hold food trays. The enclosure  12  also has a divider  40  attached to the first and second side walls  30  and  32 . The divider  40  is disposed at or about the vertical midway point of the side walls  30  and  32 . The divider  40  has a pair of generally V-shaped cutouts  42 , one proximate to the door  20  and one proximate to the back wall  28 . The back wall  28  has a pair of generally square openings, a first opening  43  and a second opening  45 , in which a first grill  44  and a second grill  46  are disposed. The first and second openings  43  and  45  link the storage compartment  24  with the outside of the enclosure  12 , allowing air to move in or out through the grills  44  and  46 . 
         [0011]    The first grill  44  is located proximate to the ceiling  34  while the second grill  46  is located proximate to the floor  36 . The first and second grills  44  and  46  permit air to flow through the back wall  28 . 
         [0012]    Referring to  FIG. 3 , an example of a refrigeration system configured according to an embodiment of the invention will now be described. The system, generally labeled  100 , includes a cart corral  102 , an air chiller  104  disposed on top of the cart corral  102 , and a duct system  106  disposed within the cart corral  102 . The duct system has an inlet  108  and an outlet  110 . The air chiller  104  has an outlet that is coupled to the inlet  108  of the duct system  106 . The air chiller  104  also has an inlet that is coupled to the outlet  110  of the duct system  106 . 
         [0013]    The duct system  106  has a main duct  112  that extends around the inner periphery of the cart corral  102 . The main duct  112  starts at the inlet  108  of the duct system  106  and terminates at the outlet  110  of the duct system  106 . 
         [0014]    The cart corral  102  has an open side  114  that enables a cart to be parked within the corral  102 .  FIG. 3  shows  3  carts, each of the carts being parked within the corral  102 . Cart  10  in this example will be assumed to have the same configuration as the cart  10  of  FIG. 1 . Each cart  10  is parked so that its front side  16  faces the open side  114  of the cart corral  102 . 
         [0015]    In addition to the main duct  112 , the duct system  106  includes a first branch  116  and a second branch  118 . The first branch  116  has openings  120  that are next to or coupled with the first openings  43  of the carts  10 . Similarly, the second branch  118  has openings  122  that are next to or coupled with the second openings  45  of the carts  10 . 
         [0016]    Disposed within the duct system  106  is a valve system, which includes a first valve  124  and a second valve  126 . The refrigeration system  100  also includes a control unit  128 . The control unit  128  includes a control circuit  130 , which controls the movement of the first and second valves  124  and  126  by sending signals to an actuator that is mechanically coupled to the first and second valves  124  and  126 . The first valve  124  has at least two positions—a first position, shown in  FIG. 3 , in which the first valve  124  directs air flowing from the inlet  108  of the duct system  106  to flow to the first branch  116 , and a second position, shown in  FIG. 4 , in which the first valve  124  prevents air flowing from the inlet  108  of the duct system  106  directly to the first branch  116 . The second valve  126  also has at least two positions—a first position, shown in  FIG. 3 , in which the second valve  126  prevents air from flowing from the first branch  116  to the main duct  112 , and a second position, shown in  FIG. 4 , in which the second valve  126  permits air to flow from the first branch  116  to the main duct  112 . 
         [0017]    The refrigeration system  100  has at least two modes of operation—a normal airflow mode and a reversed airflow mode. The normal airflow mode will now be described with respect to  FIG. 3 . In the normal airflow mode, the valve system is in a configuration in which the first valve  124  and the second valve  126  are in their respective first positions. The air chiller  104  blows chilled air into the inlet  108  of the duct system  106 . Because the first valve  124  prevents airflow directly from the inlet  108  to the main duct  112 , the air flows from the inlet  108  to the first branch  116 , and then flows through openings  120  of the first branch  116  and through the first openings  43  of the carts  10 . The chilled air flows through the storage compartment  24  of each cart  10 , through the generally V-shaped cutouts  42 , and out the second openings  45  of the carts  10 . The chilled air exiting the second openings  45  passes through the second branch  118  and proceeds to the main duct  112  and out the outlet  110 . 
         [0018]    The reverse airflow mode will now be described with reference to  FIG. 4 . In the reverse airflow mode, the valve system is in a configuration in which the first valve  124  and the second valve  126  are in their respective second positions. The first valve  124  in its second position directs airflow from the inlet  108  to the main duct  112 . With the second valve  126  in its second position, airflow from the main duct  112  is prevented from flowing directly back to the chiller  104  through the outlet  110 . Instead, the air flows from the main duct  112  into the second branch  118 , through the openings  122  of the second branch  118 , and through the second openings  45  of the carts  10 . The chilled air then passes through the storage compartment  24  of each cart  10 , through the generally V-shaped cutouts  42 , and out the first openings  43  of the carts  10 . The chilled air exiting the first openings  43  passes through first branch  116  and proceeds to the main duct  112  and back to the chiller  104  through the outlet  110 . 
         [0019]    According to an embodiment of the invention, the refrigeration system periodically switches from the normal airflow mode to the reverse airflow mode. The time interval for switching the airflow can depend on many factors, such as the desired temperature of the system, and may also depend upon a sensed temperature of the system. This could include, for example, temperature sensors that determine whether there is a difference between the temperature at the top of a cart as compared to the temperature at the bottom of a cart. If such a difference exceeds a particular threshold, the airflow may be switched to provide more uniform cooling. In one implementation, the switching may occur periodically from 2 to 30 minutes. The switching between the normal mode and the reverse mode is controlled by the control circuit  130  of the control unit  128 . Periodically reversing the flow of air helps to equalize the temperature throughout the compartment  24 . 
         [0020]    As should be appreciate by one of skill in the art, the foregoing describes an embodiment where 3 different carts are accommodated within the cooling system of the present invention. The same invention may be readily implemented with respect to more or less carts. For example, the invention may be implemented with respect to just one cart, where 2 valve are operated to direct airflow through the cart initially in one direction, then to direct airflow through the cart in the other direction. 
         [0021]    It can be seen from the foregoing that a new and useful method and system for identifying and managing currency exposure has been described. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.