Refrigeration – With repair – assembly or disassembly means
Reexamination Certificate
2001-08-06
2003-06-03
Doerrler, William (Department: 3744)
Refrigeration
With repair, assembly or disassembly means
C062S407000, C062S312000
Reexamination Certificate
active
06571571
ABSTRACT:
The present invention relates to a refrigeration unit, for example for use in a refrigerator or freezer for storing food, or for other cooling applications and chambers for cooling items. In this specification, the term refrigeration unit is used to describe the components that achieve cooling, and the term refrigerator covers the cabinet or compartment that is cooled or frozen by the cooling of the refrigeration unit.
Most commercial refrigeration systems make use of the vapour compression refrigeration cycle for cooling. This relies on the compression-condensation-expansion-evaporation cycle of refrigerant fluid. Essentially, a refrigerant fluid is expanded, for example by passing this through a throttle, thereby reducing the pressure and consequently the boiling point of the refrigerant fluid. In this state, the refrigerant fluid is able easily to evaporate and thereby absorb heat energy. In particular, heat energy can be absorbed from the refrigerator. The resulting superheated, vaporised refrigerant is then compressed in a compressor. This compression increases the pressure of the refrigerant fluid, thereby increasing its boiling point. The resulting high-pressure vapour is then condensed, causing the refrigerant fluid to give up the heat energy absorbed during the evaporation. This heat energy is emitted to the atmosphere. The refrigerant fluid, having given up all of the absorbed heat energy, is then again expanded by the throttle, reducing the pressure and therefore enabling the refrigerant to absorb further heat energy as it is evaporated as the cycle is repeated.
To make use of this cycle, a conventional refrigeration unit comprises an evaporator over which the air within the refrigerator cabinet is blown and through which expanded, low pressure, refrigerant fluid is passed. The refrigerant absorbs heat energy from the air, and therefore reduces the temperature within the cabinet. The refrigerant is then conveyed from the evaporator to a compressor where the fluid is compressed, and the resulting high-pressure vapour is condensed within the condenser, causing the absorbed energy to be dissipated from the refrigerant fluid to the atmosphere.
In many commercial refrigeration systems, the refrigeration cabinet is formed with an opening in the top through which the air is cycled and cooled. It has been known since the early 1980's to locate the components of the refrigeration unit in a plug-in box that is mounted as a single component on top of the cabinet to allow communication with the interior of the cabinet for cooling the air in the cabinet. This has the advantage that, in the event of failure of the refrigeration unit, it is possible merely to replace the entire plug-in refrigeration unit as a single component.
There are a number of problems with the use of such unitary, plug-box type refrigeration units. Firstly, such boxes are difficult and time consuming to construct. As the air from within the refrigeration cabinet passes through the plug-in box to allow cooling of the air, it is important that the box gives good thermal insulation to prevent heat from the atmosphere warming the air within the chamber. Therefore, it is usual to form the box in a similar way to the rest of the refrigerator cabinet, namely to form an outer metallic shell, an inner metallic shell spaced from the outer shell, and to fill the void between the inner and outer shells with an insulating foam material. This assembly requires the separate formation of the inner and outer shells, and the installation of spacers to ensure the required spacing between the shells. The opening between the inner and outer shells must then be sealed, for example using tape, to ensure that the void is properly filled with foam to the required density for the insulation properties required. There is a special need for good seals due to the high pressure required to inject the insulating foam to the required density. Furthermore, the high pressure used means that both the inner and outer skins must be supported during foam filling. Once the shell has been filled with the insulating foam, other components, such as baffles, must be installed individually within the box for directing airflow through the unit and past the evaporator. Components must also be added to support the parts of the refrigeration system, such as the evaporator, fans and tubes. Holes must be formed through the shell to receive the tubing for the refrigerant and power lines for the electrical components. These components cannot be installed prior to foam filling due to the need to support the inside shell during high-pressure foam filling. Accordingly, there are a large number of individual components that must be installed separately, resulting in a lot of time spent in assembling the unit. This results in a significant cost.
A second problem is that the each of the components used in the refrigeration unit itself, such as the condenser, fan, evaporator, must be individually installed in the unit, and attached to the shell by bolts or the like. Each of these components must individually be sealed to prevent any leakage of refrigerant or of the air being cooled. Again, this is time consuming and results in high manufacturing costs.
A third problem is that the design of the inside of the unit is limited due to the use of sheet metal to form the unit, and due to the need to mount components of the refrigeration unit within the box. In particular, this limits greatly the control of airflow through the unit, preventing optimisation of this. Also, it is difficult to ensure airtight seals, and so there is a risk of leakage from the desired flow path.
A fourth problem with existing designs is apparent when the units require repair. Whilst the use of a plug box allows the unit as a whole to be removed easily for replacement, in many cases it is preferred to merely repair or replace individual failed components, or to gain access to remove debris. As the boxes are formed with an open bottom, through which air flows from and to the refrigeration cabinet via the open top of the cabinet, but with solid sides, back, front and top, the only way to service the unit is through the bottom opening. When the unit is installed, this means that the only access to the inside of the unit, without removing this from the cabinet, is from the inside of the refrigerator cabinet. This means that it is necessary to empty the refrigerator cabinet to allow access to the inside of the unit. This may be inconvenient, for example in a busy kitchen where there may be nowhere else to store the contents of a refrigerator that is being repaired. Even where it is possible to empty the refrigerator, it is difficult to work inside the unit due to the limited access.
According to a first aspect of the present invention, a box for a refrigeration unit comprises a moulded, hollow walled, plastics shell, the walls of which are filled with an insulating material.
According to a second aspect of the present invention, a refrigeration unit comprises a first heat exchanger for absorbing thermal energy in fluid communication with a second heat exchanger for dissipating the absorbed thermal energy, and a means for blowing fluid to be cooled into or over the first heat exchanger such that a refrigerant passing through the first heat exchanger absorbs thermal energy from the fluid, in which the first heat exchanger is located within a box according to the first aspect of the present invention, the box further including a first opening through which the fluid to be cooled can enter the box to the heat exchanger, and a second opening through which the cooled fluid can exit the box.
An advantage of the use of a moulded plastics box is that the box may be formed automatically as a single component. This greatly reduces the amount of time required to build the box, and therefore greatly reduces the cost of manufacture of the box. A further advantage of moulding the box as a single unit is that there is no need to seal joints between components forming the box as is required with boxes formed of s
Doerrler William
Foster Refrigerator (UK) Limited
Shulman Mark S.
Thompson Hine LLP
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