This invention pertains to refrigeration control systems, and more particularly to cam operated refrigeration control systems that include refrigeration and defrost control cycles.
Defrost timers are used to control defrost heaters in freezers and refrigerator/freezers. While their application is mainly for commercial applications, many higher-end consumer refrigeration appliances also now include such defrost timers. The defrost heater prevents excessive ice build up on the evaporator coil to prevent cooling inefficiency in the refrigeration system.
In operation, the defrost timer initiates a defrost cycle after a preset compressor run time. Such compressor run times are selected based on experience with the icing phenomenon for a particular model, installation, etc. That is, it is know that a certain degree of icing on the evaporator coils is likely to have formed once the compressor has been run for a particular length of time. After such icing has likely occurred, the defrost timer initiates a defrost cycle to clear the ice from the coils to maintain the cooling efficiency of the system. The defrost timer also controls the length of the defrost cycle. The length of the defrost cycle is also preset based, once again, on typical icing conditions. That is, the defrost cycle is run for a period sufficient to remove the ice from the coils that has developed during the compressor run cycle.
As is well known, during a typical compressor operation the evaporator fan is running to circulate air over the chilled evaporator coils to cool the chamber. Unfortunately, current defrost timers operate to initiate a defrost cycle immediately after the compressor run cycle has terminated. This results in additional energy usage by the defrost heater because it has to overcome the cooling effects of the just-terminated cooling cycle. That is, immediately after the cooling cycle has ended, and for some period thereafter, the evaporator coils are still very cold from the evaporation of the coolant therein. At least until the evaporation of the coolant in the evaporator has ended, the application of energy to the defrost heater will have little effect to defrost the coils. As such, the defrost heater is simply wasting energy without effect.
There exists, therefore, a need in the art for a new and improved defrost timer that provides adequate defrosting of the evaporator coils of a refrigeration system without consuming excess energy without effect.
In view of the above, it is an objective of the present invention to provide a new and improved defrost timer. More particularly, it is an objective of the present invention to provide a new and improved defrost timer that operates to reduce the energy consumption of the defrost cycle while still providing the needed defrosting of the evaporator coils. Still more particularly, it is an objective of the present invention to provide a new and improved refrigeration control system that coordinates the operation of the components of the refrigeration system and the defrost system to provide energy efficient cooling and defrosting operation.
One embodiment of the invention provides a refrigeration control system that integrates control of the operation of a compressor, evaporator fan, and a defrost heater for a freezer/refrigerator. The refrigerant system includes a motor-operated compressor, an evaporator coil for cooling the freezer, an evaporator fan that circulates air over the evaporator coil and into the freezer compartment, and a defrost heater. The defrost heater is periodically operated to remove frost build-up from the evaporator coil.
In one embodiment, the refrigeration control system includes a motor-driven cam operated switch arrangement that includes a compressor blade, an evaporator fan blade, a defrost heater blade, and a power source blade. In this embodiment the compressor blade and evaporator fan blade contact the power source blade in a refrigeration cycle. Once the refrigeration cycle has ended, the compressor blade disconnects from the power blade such that only the evaporator fan contracts the power source blade. In this way the continued circulation of air and heat from the fan coil will begin the pre-defrosting of the coils. After the pre-defrost cycle, the evaporator fan blade disconnects from the power source blade and the defrost heater blade connects with the power source blade. This allows the defrost heater to defrost the evaporator coils in a defrost cycle mode.
Another embodiment of the invention provides an energy efficient refrigeration control method for controlling the operation of a compressor, evaporator fan, and a defrost heater in a freezer having a refrigerant system that includes a motor-operated compressor, an evaporator coil, an evaporator fan, and a defrost heater for periodically removing frost build-up from the evaporator coil. The refrigeration control method includes connecting the compressor and the evaporator fan to a power source for operation during a normal operation cycle, disconnecting the compressor from the power source so that only the evaporator fan receives power during a pre-defrost cycle, disconnecting the evaporator fan from the power source, and connecting the defrost heater to the power source for operation during a defrost cycle.
Other features and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
To overcome the above described and other problems existing in the art, the refrigeration timer control system coordinates operation of the defrost heater with the refrigeration cycle. Specifically, in the system of the present invention the energization of the defrost heater is delayed for a period of time after the compressor has been de-energized. In this way, the evaporator coils are allowed to warm, or at least are no longer providing cooling, after the refrigeration cycle has ended and the refrigerant is no longer evaporating through the coils. By delaying the energization of the defrost heater, energy is not wasted while the evaporator coils are still providing cooling due to the evaporation of refrigerant after the compressor has stopped and due to the thermal inertia of the coils themselves.
Other embodiments of the refrigeration control system of the present invention add a new cycle that allows the evaporator fan to continue to run for a period of time after the compressor has been de-energized and before the defrost heater is energized. This serves to provide a pre-warm cycle during which the relatively warmer air within the refrigerator or freezer cavity is circulated over the evaporator coils. Further, the heat from the fan coil itself provides additional warming to the evaporator prior to the defrost cycle being started while continuing to cool the air into the compartment. By delaying the energization of the defrost heater and by providing the pre-warming cycle, a net energy savings over prior systems discussed above is realized. This savings is brought about because the high wattage defrost heater is not required to run as long to defrost the evaporator coil as conventional defrost systems.
Turning now to the drawings, there is illustrated in simplified form in
As may be seen from
While not illustrated to simplify the drawings and the following discussion, those skilled in the art will recognize that a conventional motor may be provided in the assembly of
During the normal refrigeration cycle, the compressor control blade 122 and the evaporator fan control blade 106 are in contact with the electrical common blade 108 to complete the electrical circuit. This energizes the compressor and evaporator fan (not shown) via contacts 118 and 116, respectively, to provide cooling to the refrigerator/freezer. The positioning of the evaporator fan control blade 106 in relation to the spacer 104 ensures that the defrost heater control blade 110 does not come into contact with the common blade 108 during this refrigeration cycle.
As the cam 102 continues to rotate counter-clockwise from the position illustrated in
In this configuration, the compressor is de-energized but the evaporator fan is still energized. This allows the fan to continue to circulate air from the refrigerator/freezer compartment across the evaporator coils. This, along with the heat from the fan coil, pre-warms the evaporator coils to begin the defrost process. Because the evaporator fan control blade 106 is still held in this actuated position, it continues to act through spacer 104 to hold the defrost heater control blade 110 away from the common blade 108. As such, in this state only the evaporator fan is energized.
As the cam 102 continues to rotate in a counter-clockwise direction, the evaporator fan control blade 106 will encounter the cam fall 124, initiating the defrost cycle. When this occurs, as illustrated in
As may now be apparent to those skilled in the art, the present invention provides a method of controlling and coordinating the refrigeration and defrost cycles to increase energy efficiency. Indeed, some embodiments of the present invention introduce a pre-warm cycle between the refrigeration and defrost cycles to further enhance the energy efficiency of this method.
With the preceding embodiment, the compressor and the evaporator fan are bother energized simultaneously after the defrost cycle. The evaporator fan will begin circulating air immediately upon energization. However, the evaporator cannot provide cooling immediately because the evaporator coils will still be warm from the defrost cycle. As such, there is a period of time after the defrost cycle when warm moist air is circulated in the chamber, which will somewhat warm the chamber at the beginning of the refrigeration cycle. Because of this initial warming caused by the circulation of this warm post-defrost air, additional energy will need to be expended to cool the chamber.
To preclude such an occurrence, an embodiment of the invention provides an alternate blade configuration that utilizes an extra switch state to provide a compressor-only state immediately following the defrost cycle. In other words, the evaporator fan is not energized for a period after the end of the defrost cycle to preclude circulation of air across the warm evaporator coils. This state provides additional energy savings by delaying the circulation of air in the chamber until the evaporator coils have cooled.
The blade configuration of a refrigeration timer control system in accordance with this embodiment of the invention is shown in
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
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. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. 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.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
Number | Name | Date | Kind |
---|---|---|---|
2736173 | Duncan | Feb 1956 | A |
2940277 | Pas et al. | Jun 1960 | A |
3914951 | Heidorn | Oct 1975 | A |
3924416 | Durdin | Dec 1975 | A |
4392357 | Kinsey et al. | Jul 1983 | A |
20030182951 | Rafalovich et al. | Oct 2003 | A1 |
Number | Date | Country | |
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20060218946 A1 | Oct 2006 | US |