Patent Publication Number: US-2015068609-A1

Title: Apparatus for condensation reduction in a dynamically cooled air stream

Description:
BACKGROUND 
     1. Field of Use 
     This invention relates to an apparatus and method for providing a cooled, pressurized air stream to a zone around the body of an occupant in bed while avoiding generation of condensation within the apparatus enclosure or bed. The invention contemplates active feedback from sensors in the conditioned air stream to allow a microcontroller to control cooling power to the air stream to the maximum extent possible while ensuring that dewing and condensation is minimized or avoided. This measurement is achieved via a solid state relative humidity sensor located within the conditioned air stream, or a solid state dewing sensor also located in such air stream. 
     2. Description of Prior Art 
     The body of the average person releases a substantial amount of heat through skin loss and moisture due to perspiration to the surrounding air. The usual practice of covering the body during sleeping has the effect of insulating the body from the surrounding room air and thereby holds such released heat and moisture in the air about the body. 
     In cold weather when the room temperature may be below 70 F. heavy covering is frequently employed so as to minimize the exchange of air about the body with the surrounding room air and thus has the effect of increasing the air temperature and humidity about the body. In such instances a person will often throw off the covering while asleep, which will then result in chilling. 
     In warm weather when the room temperature is above 70 F., a lighter covering is usually employed but the moisture which results from perspiration is still retained about the body by the insulating covering, causing personal discomfort and results in poor rest. 
     The obese and the bedridden are particularly troubled by these conditions of the air environment about the body. Many home and hospital patients have body temperature conditions which ideally require controlled surrounding air and humidity conditions within the bed environment. 
     There are a many causes of the various known sleep disorders. Of these causes the physical comfort of the person attempting to sleep or rest is paramount, for if a person&#39;s ambient surroundings are not conducive to their personal comfort, sleep can become extremely difficult to achieve, if at all. One factor in the person&#39;s environment that has a bearing on their ability to achieve sleep is the ambient temperature. If the temperature of the surroundings of a person is either too hot or too cold, restful sleep may be impossible. Of particular concern is the case where the surroundings are too hot, because in such cases the body&#39;s ability to control its internal temperature may be effected to the point where the body begins to sweat, and it is nearly impossible to achieve restful sleep while sweating. Thus, maintaining the ambient temperature at a level which is conducive to sleep is a key to enabling a person to sleep. 
     Room air conditioners which have heretofore been provided for regulating the room air temperature and humidity conditions have the disadvantages of handling large volumes of air. requiring special electrical power, and are relatively expensive for installation, operation and maintenance costs. Even with room air conditioners, the person usually employs some form of covering which insulates the body from the surrounding air so there remains no suitable means of exchanging the air between the body and the covering of the occupant&#39;s bed. 
     Means for controlling the ambient temperature in a person&#39;s surroundings are known to include the provision of “air conditioning” in which an air conditioner utilizing the principles of Joule-Thomson cooling is employed to extract heat from a volume of air, such as a bedroom. While air conditioners are highly effective at coarsely controlling the temperature in a room, the customary preference for persons to sleep beneath one or more bed sheets, covers, blankets, etc, coupled with the body&#39;s tendency to liberate heat during its normal operation translates to the well-known situation in which the person resting beneath the sheets cannot get comfortable because they are too hot, which is compounded by the proposition that if they remove the covers or sheets from themselves then they become too cold. 
     Owing to variance between selected individual human subjects&#39; metabolism, genetics, etc. the method used in the fine tuning control of one&#39;s body temperature becomes a matter of personal taste or preference, and many individuals have typically been observed to develop their own personal habits of effecting such fine tuning, such as sleeping with more or less clothing, permitting part of the body to be exposed to the open air, etc. It is a common observation that two individuals sharing a bed may have widely different requirements of hot and cold within the ambient air of the bedding for comfortable sleep. 
     It is well understood that warm unconditioned air in contact with cooled surfaces creates condensation on those surfaces. Air conditioning an entire room creates condensation only within the cooling element of the room air conditioner, and not the room itself, as the room has been evenly filled with cool, dehumidified conditioned air that is well above the dew point of the cooled surface temperatures of the room. However, air conditioning of a small segregated space such as the zone of a bed located within a room surrounded by warm, humid unconditioned air can have disastrous impacts with unwanted condensation within the bed if the conditioned space is cooled to below the dew point of the room air. Further, if the air conditioning device is located as an attachment to the bed and not connected to an outside window or wall, there is no means to dispose of the condensate accumulation on the cooling elements other than storing it and requiring regular disposal. 
     In spite of these efforts, perfect control of the temperature of ambient surroundings of persons in a bed desiring to sleep has been fleeting, with particular difficulty for sleepers who continually feel too hot and could benefit from an active cooling control over their beds. This fact is evidenced by the myriad of schemes and contrivances provided by workers in the prior art for effecting thermal control and cooling over a bed or region in which a person normally rests for sleep utilizing a pressurized flow of cool air, the following few of which are exemplary, and are herein incorporated by reference in their entirety. 
     U.S. Pat. No. CA 2,295,584 C sets forth An apparatus for cooling a patient, comprising: an upper sheet and a base sheet connected together at a plurality of locations to form an inflatable covering, the inflatable covering including: an inlet for receiving pressurized air in the inflatable covering, and a plurality of apertures extending through the base sheet for exhausting the pressurized air from the inflatable covering; and a liquid distribution apparatus disposed beneath the base sheet to deliver a liquid adjacent a region of the base sheet including at least a portion of the apertures for being evaporated by the pressurized air exhausted from the inflatable covering. 
     This invention is deficient because it requires a liquid distribution into the bedding and relies on an evaporative method for cooling, thus introducing excess moisture into the bedding if the system is operated in other than dry climates. 
     U.S. Pat. WO 2014022419 A1, teaches a method for operating an air conditioning system configured to deliver conditioned air to a supporting apparatus, the method comprising: 
     receiving user input and operating the air conditioning system according to an operation cycle, wherein during the operation cycle the air conditioning system generates conditioned air; 
     measuring, during the operation cycle, relative humidity of ambient air in which the air conditioning system is disposed; and 
     adjusting operation of one or more thermoelectric devices (TEDs) within the air conditioning system in response to the measured relative humidity to control condensation generation within the air conditioning system. 
     This invention relies on measurement of ambient room air relative humidity combined with microprocessor driven calculations and a calibration lookup table (see Invention Drawings Table 1.0 and 1.1) to avoid powering the cooling element TED&#39;s above a limit that will generate condensation. This method of measuring ambient room humidity can provide some level of condensation reduction under optimal conditions that must be built into the lookup table calibration assumptions. However, this method is also deficient for maximizing available cooling power while simultaneously providing optimum condensation reduction for the following reasons:
         1) It requires a pre-programmed lookup table for microprocessor calibration of the apparatus cooling power versus relative humidity to avoid achieving dew points. This calibration table can only be based off a single starting set point of component performance assumptions or environmental conditions that may change over time   2) Standard absolute pressure can alter the amount of condensable water in ambient air at the same relative humidity measurement levels, the Invention claims no pressure sensor element to compensate for this. This deficiency can result in changing standard pressure conditions where either condensate may be formed or where the maximum amount of cooling that could be provided without condensate being formed is not provided by the invention due to reliance on the lookup table.   3) Degradation over time of the power vs. efficiency of the TED&#39;s may alter the effective cooling provided to the airstream, effectively throwing the calibration of the lookup table off and causing the invention to provide lower amounts of cooling than could be provided without condensation forming   4) Air filters that become clogged over time will result in lower than expected air flow through the system. This slower moving air will cause air flow through the cooling TED&#39;s to drop in temperature more than calibrated for in the lookup table and thus causing increasing condensation; a means for compensating for this is to assume a clogged filter in the calibration table, but this then provides the deficiency of providing less cooling that could be otherwise provided without generating condensation   5) Degradation in the supplier air fan motor due to aging or bearing degradation can result in lower flow than originally calibrated for, causing the same deficiency as in #4 above   6) Higher static pressure in the air flow exhaust than expected due to kinks air flow in hoses, poor installation of the air distribution method, or variability in manufacturing of the air distribution method can result in lower air flows than expected, causing the same deficiency as in #4 above       

     While each of the prior art devices and methods achieve to a greater or less extent their desired objectives, they are nevertheless not without features which have heretofore prevented their widespread adoption by large numbers of people. The prior arts fails to teach a cooling apparatus that can maximize the possible dynamic cooling power for a flow of air into the zone of a bed occupied by the sleeper, under all possible unknown, unforeseen or unpredictable environmental and system component degradation conditions, while simultaneously avoiding condensation formation both in the bed and inside the apparatus. 
     Thus, there exists a need for an improved apparatus and method for providing a pressurized flow of air that is dynamically cooled to the maximum extent possible while avoiding condensation in the apparatus or any subsequent conditioned air flow zones which may be in contact with unconditioned air, and that includes the novel features of:
         Fast response of cooling power against the actual real formation of condensation in the air flow without have to resort to a microprocessor stored lookup table and prior calibrations that assume when condensation will be forming based of a calculation   Maximum cooling power provided regardless of fan degradation, air filter clogging, cooling element degradation, higher than expected static pressures in the exhaust path, or any other unexpected factors which lower fan flow below expected flow rate setpoints       

     BRIEF SUMMARY 
     The foregoing and other problems are overcome, and other advantages are realized, in accordance with the presently preferred embodiments of these teachings. 
     It is a primary aim and object of the present invention to provide an apparatus and method of operation that can provide the maximum amount of cooling to a conditioned flow of air with little or no condensation formation while dynamically adapting to a wide range of environmental and component degradation issues such as clogged air filters, kinked air flow paths, degradation in cooling element efficiency, degradation in fan motor performance, and variability in air distribution methods or manufacturing. 
     Another object of the invention is a cooling element that provides means for cooling the conditioned air stream, such cooling element being capable of variable cooling power by a microcontroller. This cooling element can be a thermoelectric device, or variable speed compressor refrigeration loop. 
     Yet another object of the invention is a means for providing pressurized air flow such as a fan or blower 
     Yet another object of the invention is the location of a dewing sensor, or humidity sensor directly within the conditioned air stream very near or on the cooling elements. This allows real time measurement of actual imminent formation of condensation regardless of any external condition or room air ambient relative humidity. 
     Another object of the invention is a microcontroller, that can receive measurements from the dewing sensor or humidity sensor and ramp the cooling power of the cooling elements up and down around a simple pre-set dewing sensor or humidity sensor measurement set-point. 
     Another possible embodiment of the invention is inclusion of a heating element such that the apparatus can supply both heated and cooled air 
     In accordance with another embodiment of the invention another feature of the apparatus is the supply of conditioned air to other apparatus that can distribute the flow of conditioned air into a mattress or zone of a bed occupied by a sleeper 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
     
    
    
     DETAILED DESCRIPTION 
     The following brief definition of terms shall apply throughout the application: 
     The term “comprising” means including but not limited to, and should be interpreted in the manner it is typically used in the patent context; 
     The phrases “in one embodiment,” “according to one embodiment,” and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment); 
     If the specification describes something as “exemplary” or an “example,” it should be understood that refers to a non-exclusive example; and 
     If the specification states a component or feature “may,” “can,” “could,” “should,” “preferably,” “possibly,” “typically,” “optionally,” “for example,” or “might” (or other such language) be included or have a characteristic, that particular component or feature is not required to be included or to have the characteristic. 
     Referring now to  FIG. 1 , there is shown a block diagram illustration of an operational use in which the invention is implemented. Item  8  identifies the flow path of air through the apparatus; Item  1  represents a removable washable air filter; Item  2  represents the fan or blower that creates the pressurized air flow, this item being optional in one embodiment of the invention; Item  3  representing an optional heating element; Item  4  representing the variable powered cooling element; Item  5  representing the dewing sensor or humidity sensor; Item  6  representing a mechanical outlet connection for the conditioned supply of air to another apparatus for delivery to a bed or mattress; Item  7  representing the microcontroller which receives sensor signals from Item  5  and appropriately dispatches the cooling element with higher or lower power.