Patent Grant
12241681
The present invention relates generally to a system for and method of monitoring for and predicting the failure of a cooling system resulting from the failure of one or more components.
Cooling systems are used to provide temperature control in a variety of different applications. Some examples include refrigerators, freezers, and indoor climate control. A typical cooling system employs a compressor that compresses a gas, a first heat exchanger that removes heat from the compressed gas, an expansion device that allows the compressed gas to expand into a chamber which is generally a second heat exchanger. The second heat exchanger extracts heat from its surroundings, providing a refrigeration function. While the example applications generally involve heat exchangers designed to interface with air, certain implementations can be configured to transfer heat to or from liquids. Additionally, the system described can be used to heat rather than cool. Many cooling systems using the components and methods described simply cycle the compressor on and off. During the on-time of the compressor, the temperature of the gas in the second heat exchanger rapidly cools the heat exchanger to a certain temperature level. During the off-time, the heat exchanger warms to a level that approaches the temperature of the environment in which is it located. As a result, the environment in which the heat exchanger is located also exhibits a cyclic temperature variation.
When cooling systems are used to maintain the environmental conditions for food, medications, or other perishable items, the failure of the cooling system can result in a significant financial loss or a danger to persons in need of the medications. As with many mechanical systems, compressors and valves wear and tubing leaks, resulting in the eventual failure of the cooling system. A system and method of detecting an impending failure is needed to detect failure sufficiently in advance of the actual failure such that action may be taken to prevent loss of, or damage to, food, medications, or perishable items.
In exemplary embodiments, a temperature associated with a first heat exchanger is measured over a period of time and variations of that temperature are compared to a baseline temperature variation. The characteristics of the measured temperature are evaluated for indication of impending failures where the characteristics may comprise such measurements as maximum temperatures, minimum temperatures, the length of time that passes between the maximum and minimum temperatures, the frequency of the maximum or minimum temperatures, the rate of change of temperature, or the variation of rate of change as the temperature either increases or decreases over time.
In another exemplary embodiment, a pressure measured in a Cooling system over a period of time and a variation of that pressure is compared to a baseline pressure. The characteristics of the measured pressure are evaluated for indication of impending failures where the characteristics may comprise such measurements as maximum pressure, minimum pressure, the length of time that passes between the maximum and minimum pressures, the frequency of the maximum or minimum pressures, the rate of change of pressure, or the variation of rate of change as the pressure either increases or decreases over time.
In another exemplary embodiment, a compressor current draw measured in a Cooling system over a period of time and a variation of that current draw is compared to a baseline current draw. The characteristics of the measured current draw are evaluated for indication of impending failures where the characteristics may comprise such measurements as maximum current, minimum current, the length of time that passes between the maximum and minimum currents, the frequency of the maximum or minimum currents, the rate of change of current, or the variation of rate of change as the current either increases or decreases over time.
The above summary is not intended to describe each illustrated embodiment or every implementation of the invention. Rather, the embodiments are chosen and described so that other skilled in the art can appreciate and understand the principles and practices of the invention. The figures and the detailed description that follow more particularly exemplify these embodiments.
These and other features and advantages of the present invention will become better understood with regard to the following description and accompanying drawings in which:
While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. The drawings thus provide illustration and a further understanding of the various aspects and implementations, and are incorporated in and constitute a part of this specification. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims. These and other aspects and implementations are discussed in detail below. The foregoing information and the following detailed description include illustrative examples of various aspects and implementations, and provide an overview or framework for understanding the nature and character of the claimed aspects and implementations.
As used herein, the term Cooler refers to a container for keeping items such as, without limitation, food, drink, or medications, at a regulated temperature. As used herein, the term cooler can be used interchangeably with refrigerator, freezer, pharmacy cooler, pharmacy freezer, or other devices that regulate temperature.
As used herein, the term Cooling System refers to a system that regulates the temperature at which items may be stored.
As used herein, the term User refers to a person or organization that stores items in a cooler.
As used herein, the term Learning Cooler refers to a cooler that has parameters (i.e., Upper Time Limit and Lower Time Limit) that may change over time, based on past cooler characteristics.
As used herein, the term Non-Learning Cooler refers to a cooler that has parameters (i.e., Upper Time Limit and Lower Time Limit) that are manually set.
As used herein, the term Upper Temperature Limit refers to a desired maximum temperature a cooler may exhibit for a period of time.
As used herein, the term Upper Time Limit refers to the duration a cooler's temperature may remain above its Upper Temperature Limit. Once the duration has been exceeded, a notification may be sent to a user.
As used herein, the term Lower Temperature Limit refers to a desired minimum temperature exhibited by a cooler for a period of time.
As used herein, the term Lower Time Limit refers to the duration a cooler's temperature may remain below its Lower Temperature Limit. Once the duration has been exceeded, a notification may be sent to a user.
As used herein, the term Notification Interval refers to the unit of time to send reminder notifications of a persisting issue of a cooler after a first notification has been sent.
As used herein, the term Notification Count refers to the total number of notifications a user could receive for a single condition detected in a cooler.
Referring again to
In an exemplary embodiment, the monitoring system 102 monitors the temperature inside the enclosure 112 using a temperature sensor 118. In such an exemplary embodiment, the monitoring system learns the temperature characteristics of the enclosure 112 in response to conditions such as compressor activity, door open or close activity, ambient temperature, etc. The monitoring system 102 may learn the typical temperature cycle (a lowering or raising of a monitored temperature during normal operation of the compressor).
In certain exemplary embodiments, peak detection is used to identify local maximum (peak) temperatures that exceed the upper temperature limit by a comparison of neighboring temperature values. As is shown in the graph of temperature over time 300 of
As is illustrated, peak temperature cycles are the durations during which a cooler's temperature remains above upper threshold 304. Many cooling systems 100 utilize heating systems or other methods to remove ice that may accumulate on the first heat exchanger 106. During the process of removing accumulated ice (often referred to as a “defrost cycle”), a heater located proximally to the heat exchanger 106 is energized while the compressor is held in an off state. This causes a micro-climate at the heat exchanger in which the temperature is high enough to cause the accumulated ice to melt from the heat exchanger. Because the compressor is not engaged and heat is introduced into the enclosure 112, higher than expected peak values 306 or longer than expected peak temperature cycles 308 may occur during a normal defrost cycle. However, similar peak values 306 or longer than expected peak temperature cycles 308 may also occur during abnormal circumstances such as a cooler door being accidentally left open, or a compressor 104 or control failure. As a result, certain exemplary embodiments may also monitor compressor 104 activity or door sensors (not shown).
An exemplary embodiment uses peak detection as well as temperature measurements over time to learn the normal duration of a cooling system's 100 peak temperature cycle 308. Thus, the monitoring system 102 “learns” what is normal with regard to the amount of time a cooling system's 100 temperature remains above its upper threshold 304 (the peak temperature cycle 308). This time duration is used to derive a normal or ordinary amount of time that a cooler's temperature will exceed the upper threshold 304. The monitoring system 102 uses this normal or ordinary amount of time to set an alert that is delivered to a user when the cooler temperatures exceed the set point for a duration longer than the normal or ordinary time. In an exemplary embodiment, the time that exceeds what has been determined to be normal or ordinary can be combined with other temperature cycle characteristics to determine the likely severity of the problem or failure which gave rise to the alert. An example of this is illustrated in
In addition to the peak temperature cycle 308, peak detection allows an exemplary embodiment to characterize the behavior of a cooling system 100 to enable predictive analytics. For example, an exemplary embodiment may detect and monitor the maximum temperature 306 a cooling system 100 ordinarily reaches during its peak temperature cycles 308, the number of peak temperature cycles 308 that usually occur during a time period, the normal amount of time between peak temperature cycles 308, or the slope or other characteristics of temperature rise or fall. For example, a steeper slope of temperature rise may indicate that a door to a cooling system has been left ajar, a less steep slope during temperature fall might indicate that there is a pending failure of the compressor 104 or other cooling system 100 component.
Certain exemplary embodiments utilize a valley detection or time below lower temperature limit analysis. An example of this is illustrated in
After peak temperature cycle 308 and valley temperature cycle 506 durations have been calculated by an exemplary embodiment, an Empirical Cumulative Distribution Function (ECDF) is calculated for each temperature cycle type. An ECDf is calculated for peak temperature cycle 308 durations and for valley temperature cycle 506 durations. In an exemplary embodiment, ECDFs are used to estimate the probability of a cooler behaving a certain way based on its historical behavior.
For the above example, an ECDF allows us to estimate the probability of a cooler's peak temperature cycle lasting a specific duration or less based on historical observations. As is shown in the peak cycle duration distribution graph 600 of
In an exemplary embodiment, alerting time selection is buffered to limit unnecessary alerts. For example, data from a cooling system 100 has been collected by a monitoring system 102. The data has been analyzed and it has been determined that the cooling system 100 has several consistent peak temperature cycle durations, all between 15-20 minutes each. In this example, selecting an upper time limit threshold of 20 minutes would most likely result in nuisance alerts to a user because a peak temperature cycle duration lasting 21 minutes would send an alert when in reality, there may be no cause for alarm. In order to address such nuisance alerts, a time selection buffer can be employed. Based on the sample size of the observations, a time buffer is applied to the alerting time limit selected. In an exemplary embodiment, large sample sizes will have a smaller time buffer (i.e., 10 minutes) while smaller sample sizes will have a larger time buffer (i.e., 30 minutes). The larger time buffer is required due to a lower level of certainty provided by small sample sized.
Exemplary embodiments employ historical data to predict what incidents are abnormal for a cooling system. In order to avoid using abnormal data to establish what is “normal” for a cooling system, a method of distinguishing between normal and abnormal observations is needed. For example, when learning what is normal for peak temperature cycle durations, it would be undesirable to set an upper time limit too high as the result of an event during which the cooler's peak temperature cycle duration was actually abnormally high. In order to distinguish between what is normal and abnormal, Median Absolute Deviation (MAD) is used as a measure to identify outliers in a cooling system's historical data. MAD is used in certain exemplary embodiments due to its ability to adjust to various sample sizes (i.e., some cooling systems may not have a sample size that comprises a sufficient number of data samples to properly learn from) and varying data distributions. The ability to adjust to different data distributions is critical because research has indicated that not all cooling systems exhibit cycle duration data that follows a common distribution pattern.
The
In an exemplary implementation, critical failures of a cooling system used for refrigeration of perishable food items must generally be addressed within four hours of the failure to prevent damage to the contents of the refrigerator. Therefore, in such an exemplary implementation, an upper boundary of three hours for a time limit selection is used to ensure that a monitoring system according to an exemplary embodiment provides a warning to users that alerts them to a detected or predicted failure before this four-hour period elapses. In order to determine a selection of lower time boundaries, testing of an exemplary embodiment was initiated with a one-hour lower time limit. Initial observations revealed that normally operating cooling systems used in refrigerators generally have peak temperature cycle durations of around 30-45 minutes. In light of these observations, a lower time boundary of 60 minutes was chosen to provide a small buffer of time between an elapsed time that would generate an alert and the normal time periods observed during testing.
In some exemplary embodiments, the processor 202 of a monitoring system 102 may be configured to learn how a particular cooling system behaves in order to narrow the range of peak cycle durations that should be considered as indicative of an actual or pending failure. As more data is received and analyzed, certain exemplary embodiments will continue to refine the time boundary limits in order to alert users as quickly as possible while avoiding false failure indications.
In certain exemplary embodiments, data collected by the monitoring system 102 can be provided to a monitored data analysis system 120 (see
Having now described some illustrative implementations, it is apparent that the foregoing is illustrative and not limiting, having been presented by way of example. In particular, although many of the examples presented herein involve specific combinations of method acts or system elements, those acts and those elements can be combined in other ways to accomplish the same objectives. Acts, elements, and features discussed in connection with one implementation are not intended to be excluded from a similar role in other implementations.
The hardware and data processing components described in
The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The exemplary embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.
The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” “comprising” “having” “containing” “involving” “characterized by” “characterized in that” and variations thereof herein, is meant to encompass the items listed thereafter, equivalents thereof, and additional items, as well as alternate implementations consisting of the items listed thereafter exclusively. In one implementation, the systems and methods described herein consist of one, each combination of more than one, or all of the described elements, acts, or components.
Any references to implementations or elements or acts of the systems and methods herein referred to in the singular can also embrace implementations including a plurality of these elements, and any references in plural to any implementation or element or act herein can also embrace implementations including only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements to single or plural configurations. References to any act or element being based on any information, act or element can include implementations where the act or element is based at least in part on any information, act, or element.
Any implementation or embodiment disclosed herein can be combined with any other implementation or embodiment, and references to “an implementation,” “some implementations,” “one implementation,” “an embodiment,” “some embodiments,” “certain embodiments,” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the implementation can be included in at least one implementation or embodiment. Such terms as used herein are not necessarily all referring to the same implementation. Any implementation or embodiment can be combined with any other implementation or embodiment, inclusively or exclusively, in any manner consistent with the aspects and implementations disclosed herein.
Where technical features in the drawings, detailed description or any claim are followed by reference signs, the reference signs have been included to increase the intelligibility of the drawings, detailed description, and claims. Accordingly, neither the reference signs nor their absence have any limiting effect on the scope of any claim elements.
Systems and methods described herein may be embodied in other specific forms without departing from the characteristics thereof.
References to “or” can be construed as inclusive so that any terms described using “or” can indicate any of a single, more than one, and all of the described terms. A reference to “at least one of ‘A’ and ‘B’” can include only ‘A’, only ‘B’, as well as both ‘A’ and ‘B’. Such references used in conjunction with “comprising” or other open terminology can include additional items.
Modifications of described elements and acts such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations can occur without materially departing from the teachings and advantages of the subject matter disclosed herein. For example, elements shown as integrally formed can be constructed of multiple parts or elements, the position of elements can be reversed or otherwise varied, and the nature or number of discrete elements or positions can be altered or varied. Other substitutions, modifications, changes and omissions can also be made in the design, operating conditions and arrangement of the disclosed elements and operations without departing from the scope of the present disclosure.
References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the Figures. The orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
Various embodiments of systems, devices, and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the claimed inventions. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the claimed inventions.
Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the subject matter hereof may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the various embodiments can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted.
The present application claims priority to provisional U.S. Patent Application No. 63/077,014, filed on Nov. 9, 2020.
| Number | Name | Date | Kind |
|---|---|---|---|
| 20180128713 | Kriss | May 2018 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 63077014 | Sep 2020 | US |
