Refrigeration – With indicator or tester – Position or extent of motion of movable element
Reexamination Certificate
2001-03-14
2002-06-11
Tanner, Harry B. (Department: 3744)
Refrigeration
With indicator or tester
Position or extent of motion of movable element
C062S180000, C062S264000
Reexamination Certificate
active
06401466
ABSTRACT:
COPYRIGHT NOTICE
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
The present invention relates to devices designed to provide for controlled environments wherein personnel would be required to have access to, and periodically be required to work in these controlled environments. Many types of environments which provide for control of parameters such as temperature, humidity and the like may be fitted with the invention, but the primary application for the device is in utilization with environments such as walk-in coolers and freezers.
Specifically, the present invention relates to a device which incorporates both a switch means such as a magnetic contact mounted on the compartment door and door frame to sense status of the door being opened or closed, and a manually operated push button switch located inside of the compartment with functional integration between the two switches as sensors for the operation of the invention. Opening or closing of the compartment door or activation of the push button will cause the device to perform its intended functions, which include interruption and restoration of normal operation of systems and components that are in place to provide creation of the desired environment such as a refrigeration system, control of interior lighting which is provided for illumination of the compartment when personnel are inside and control of an audible, visual and remote notification annunciation system to indicate conditions such as the door being left ajar or operational conditions where annunciation to the user of pending or other functions of the device is desired.
BACKGROUND OF THE INVENTION
Principles of operation of refrigeration systems for walk-in coolers and freezers and the physical designs of these compartments are fairly standardized and well documented. An inherent component of walk-in coolers and freezers is the door and the doorway which provides access to the interior of the compartment. Obviously, this door and doorway are utilized by personnel as a means of entering and exiting the compartment to perform various tasks such as retrieving or returning perishables, stocking, cleaning, doing inventory and the like. While necessary for utilization of the compartment, opening of the door can have detrimental effects on overall system tags performance and can also have impact on perishable items that are contained within the walk-in. Whenever the door is opened, cold inside air is exchanged with warmer outside air, resulting in a substantial expenditure of energy needed in attempting to maintain compartment temperature as the system will constantly be calling for refrigeration to compensate for the door opened condition. This is particularly the case when the door is to be opened for a prolonged period of time such as when a compartment is being stocked with product. The thermal exchange of air that takes place also causes air outside of the compartment to drop in temperature which can be undesirable as well. In severe cases when a door is left open for too long a period of time or if a door is accidentally left ajar, this can cause damage to or spoilage of the product that is contained in the compartment.
Another matter of concern with walk-in coolers and freezers is exposure of personnel to the environment created by the operating refrigeration system. Attempting to perform any of the aforementioned operational or maintenance tasks with the refrigeration system running exposes personnel to abnormally cold temperatures, particularly in walk-in freezers. This condition becomes more dramatic when personnel have work to do inside of a compartment for a prolonged period of time and have elected to work with the door closed so as to minimize thermal exchange. In these instances, temperatures can become extremely uncomfortable and even life threatening.
Another component that is integral to virtually all walk-in coolers and freezers is illumination means for the interior of the compartment. These illumination means are typically controlled by a light switch adjacent to the door of the compartment. Operation of the light switch is personnel dependent with the result being that lights are often left on unnecessarily when the door is closed. While this does not adversely affect performance of the compartment or compromise product integrity, it nevertheless causes an unnecessary waste of energy and thus increases operating expenses.
There are numerous devices and techniques known in the field which, independently or in combination, attempt to address these situations. For example, regarding refrigeration functions, there are various timing devices, both mechanical and electronic, which can be used to disable operation of the fans and solenoid valve so as to temporarily interrupt operation of the refrigeration system. These devices are typically manually activated and will interrupt operation for a selected period of time after which the refrigeration system will automatically restart. While these devices are effective for their intended purpose they are limited in that they only respond to their internal timing mechanisms and have no connection with functional operation of the box such as whether the door is opened or closed. They will only turn refrigeration back on when they have “timed out”, even if the task for which they have been activated has been completed and ideally, the refrigeration system should have restarted.
Another approach often used is to mount a switch on the door frame which deactivates the fans and solenoid valve when the door is opened and reactivates them when the door is closed. However, this method has a number of disadvantages. Firstly, turning components on and off every time the door is opened or closed can cause excessive wear to the solenoid valve, the fans and the compressor. This is particularly true of food service facilities, where doors can be opened and closed frequently, especially at busy times of the day when personnel are entering and exiting the compartment to retrieve and return perishable items. Secondly, this approach does not provide a means for working inside of the compartment with the refrigeration off when the door is closed. Thirdly, this approach can result in catastrophic product loss if a door is left even slightly ajar as the refrigeration system in this scenario would not turn back on. All of these represent significant shortcomings to utilizing this method.
There are also manually operated techniques that are utilized such as switches that will allow personnel to shut off the fans and solenoid valve so as to temporarily de-activate the refrigeration system when so desired. However, these methods rely on human responses for proper operation and thus suffer from the same flaws as those that are apparent with light switches. If personnel fail to re-activate the refrigeration system the results can be disastrous with substantial loss of perishable items.
Regarding audible, visual and remote notification capable annunciation systems there are well known approaches and techniques which exist in the prior art that sense the status of the door and provide a door ajar alarm if the door is opened for too long. Some of these devices even incorporate a timed relay function to provide some interruption and restoration capability of the operation of the refrigeration system in response to the door being opened or closed. However, because of the limited capabilities of devices which are only a door ajar alarm or even in devices which offer some interruption and restoration capabilities, the annunciation system functions only as a door ajar alarm and it is not designed or intended to annunciate any other pending functions of the device. Also, none of these devices offers a means for activation oth
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