Patent Application
20080202516
The human thermo-regulatory system maintains the human body core temperature within 0.2° C. of 37° C. When this core temperature deviates significantly metabolic deterioration takes place and even death may result. Various studies of surgeries have shown that a 1° C. to 2° C. hypothermia is empirically associated with increased mortality rates with triple the rate of cardiac episodes, triple the incidence of surgically related infections, and prolonged hospitalization. Hypothermia is also implicated in significant increases of surgical blood loss thereby increasing the incidences of blood transfusions. Hypothermia has been categorized as either: mild (32.2° to 35° C.); moderate (27° and 32.2° C.); or severe (<80° F. or 27° C.) based on core body temperature as opposed to tactile or skin surface temperature readings that often belie the onset of hypothermia. Hypothermia based upon core body temperature assay often manifest in the symptoms of clinical depression, shivering, and increased pulse and metabolic rates, dysarthria, ataxia, and apathy. If the core body temperature goes below 90° F. or 32.2° C. the body loses its ability to shiver and re-warm spontaneously.
Whole body cooling is used clinically to protect the brain in some cardiac and neurologic patients. Hyperthermia (>2.0° C.) is also associated with adverse medical effects. Body core temperatures that are outside homeostatic limits are maybe afflicted with significant illness, which contributes or may cause their temperature deviation but temperature change itself may contribute to system dysfunction, however, many occupations expose workers to extremes in temperature by environmental exposure and not otherwise associated with an illness.
Core body temperature is normally regulated by the brain primarily by the hypothalamus. The brain integrates thermal inputs from: the skin surface; the lower neural centers; and the deep tissues with threshold temperatures that trigger each thermoregulatory response. This temperature information is generally processed in the spinal cord and brain stem prior to its receipt by the hypothalamus, however, there are some thermoregulatory responses that originate solely from the spinal cord.
It is well known in the art that the treatment of core temperature changes, either hypothermia or hyperthermia can be either passive or active. One common treatment of hypothermia is submersion in warm water (104° F. or 40° C.) however this is often dangerous because core temperatures may continue to fall as the surface is heated. More practical methods that are used in the art include heated inspiratory air (oxygen), warmed IV solutions, application of warmed blankets, and for more severe cases body cavity lavage with warm saline, and warming with extracorporeal blood circulation with or without cardiac bypass. Hyperthermia is treated with medications and surface cooling with alcohol baths or cooling blankets, however, it appears that the cooling of inspiratory air for treatment of hyperthermia is not known.
The human lungs perform vital functions in the human body. The most important lung function is of course to take in oxygen and remove carbon dioxide to and from the pulmonary blood flow through the lungs. The air taken in with each breath enters the lungs by the main windpipe called the trachea. The trachea then branches into two main tubes called the bronchi supplying the right and left lung, respectively. These bronchi branch 22 additional times to form more than 100,000 smaller tubes called bronchioles and collectively containing more than 300 million air sacs called alveoli which average 0.3 mm in diameter.
The surface area of the lungs of the average sized person (70 kg or 154 lbs) has been calculated to equal 900 ft2, which is larger than the surface area of a tennis court. In contrast the average sized person's skin surface area is only 1.8 m2 (19.4 ft2). Because the walls of these air sacs are 1/50th the thickness of tissue paper and are bathed in blood by millions of capillaries, there is an easy and efficient exchange of temperature between the body and the environment through the inhalation of air.
Simple calorimetry and the physics of thermal conductivity make it readily apparent that the potential heat exchange with the human body through the pulmonary system as opposed to the skin is 46 times greater based upon surface area contact alone. Furthermore, the physiology of the human body is such that often times the brain and spinal cord thermo-regulatory response to the skin causes a reduced circulation of blood to the extremities including the skin, thus further reducing the possibility of controlling core temperatures by skin exposure to heating and cooling devices. The pulmonary system cannot and does not react in the same manner since oxygenation of the blood by the lungs must continue or death would result. Therefore by heating inspiratory air in cases of hypothermia and cooling inspiratory air in cases of hyperthermia will directly affect body core temperatures. It should be noted that the thermal efficiency of the lungs is so high that regardless of the temperature of inspired air, the exhausted air from the lungs (except in extreme cases where body core temperatures are near fatal) is constant which is due in large measure to the evaporative and convective heat loss ability of the lungs. Pulmonary evaporative heat loss amounts to an average of one-third or more of the average person's entire evaporative heat loss depending upon the lung capacity of the individual, the atmospheric pressure, relative humidity, clothing and the respiration rate.
This body temperature heat exchange is calculated using the formula: S=(M+W)+R+C+(Cresp+Eresp)+E. A positive value for any of these terms signifies that the body core has gained heat, and a negative value indicates heat loss from the body core. Each of the terms represents an energy transfer rate. These rates are often normalized values to body surface area.
In the formula term S is the Heat Storage Rate. If the S value is zero then the body is in considered to be in thermal equilibrium with heat gain being balanced by heat loss. If the S value is positive then the body is gaining heat at the rate indicated by the value of S.
In the formula term M is Metabolic Rate. The rate of metabolism depends directly on the rate and type of external work currently being demanded. The W term is External Work Rate which is the amount of energy that is converted from biochemical energy to mechanical work. The W value is typically only about 10% of M. The W value is generally small relative to the other heat exchanges found in industrial applications so therefore the value is generally ignored.
The R term is the Radiant Heat Exchange Rate (Radiation). This is the rate of heat transfer by radiation which depends on the average temperature of the surrounding solid surfaces, skin temperature, and clothing.
The C term is the Convective Heat Exchange Rate (Convection). This is the exchange of heat between the skin and the surrounding air. The direction of heat flow depends on the temperature difference between the skin and air. If the ambient air temperature is greater than the skin's then the C term is positive and heat flows from the air to the skin. The rate of convective heat exchange depends on the magnitude of the temperature difference, the amount of air motion, and clothing.
The Cresp term is the Rate of Convective Heat Exchange by Respiration. The fact that air is moved in and out of the lungs, which have a surface area on average 46 times that of the skin, there is a huge opportunity to gain or lose heat by lung convection. The rate of heat exchange depends on the air temperature and volume of air inhaled. Adding to the lungs massive potential for heat exchange is the Eresp term which is the Rate of Evaporative Heat Loss by Respiration. Again the incredibly large surface area of the lungs provides an additional opportunity to lose heat with the pulmonary system (lungs) by evaporation. The rate of Eresp heat exchange depends on the air humidity and volume of air inhaled.
The E term is the Rate of Evaporative Heat Loss which for an average individual amounts to about ⅔ of the total evaporative heat loss of the body. Sweat on the skin surface will absorb heat from the skin when evaporating into the air. The process of evaporation cools the skin and, in turn, the body. The rate of evaporative heat loss depends on the amount of sweating, air movement, ambient humidity, and clothing, all of which can vary widely from one individual to the next.
The goal in design and usage of personal cooling and heating devices is to maintain the storage rate (S) at zero by controlling body surface temperatures or pulmonary air intake temperatures sufficient to remove (or add as the need may be) the heat generated by metabolism plus any heat gained from (or lost to) the environment through R+C. Again, because the surface area of the lungs are 46 times that of the skin, through convective and evaporative pulmonary heat transfer the cooling and/or heating of inspiratory air is not only the most effective, from an energy standpoint it is the most efficient.
There is a long felt need for a personal cooling and heating system that does not require the user to add or remove clothing. Military and law enforcement personnel have a need to cool themselves when is extreme heat conditions such as desert environment. More often than not, these individuals are required to wear a heavy uniform and ballistic protection gear. In yet other situations, military and civilian personnel that are required to use Chem-Bio gear have no way to cool themselves and consequently they experience an effective use time that is generally no more than 40 minutes before they run the risk of passing out from heat exhaustion.
Other technologies utilize a cooling garment worn next to the skin generally over a thin undergarment (i.e. “silks” or thin T-shirt), that the user then is required to wear underneath all their other clothing and gear. These garments generally have plastic tubing with chilled liquid running through them. This is considered the state of the art technology, however these types of systems are very inefficient and have a very short (2-3 hour maximum) power capacity with only 200 watts of cooling capability on average.
These systems manifest the following limitations:
There are no acceptable prior art heat stress and cold weather exposure relief systems for individuals, such as soldiers, operating in hot and cold environments for extended periods of time. Desert conditions for example often place individuals in a heat stress environment during the daylight hours and in severe cold during the nighttime. Heat stress can result in sweating, fatigue, dehydration, dizziness, hot skin temperature, muscle weakness, increased heart rate, heat rash, fainting, injuries, weight loss, heat stroke, heat exhaustion, and even death. The risk of heat stress is even greater for those wearing nuclear, biological and chemical (NBC) protective clothing, as well as aircrew personnel wearing flight gear. Cold weather exposure can cause discomfort; pain; numbness; cardiac, circulatory and respiratory problems; diminished muscle function and performance; frostbite, and hypothermia which can lead to unconsciousness and death.
While a portable, lightweight, low power, personal cooling and heating system can reduce heat stress, reduce the adverse effects of cold exposure, improve performance, and reduce water consumption, current active and passive cooling systems fall short of meeting the minimum requirements for an optimal system.
Active personal cooling devices are well know in the prior art. Also active personal heating systems are known in the prior art. The prior art, however, seems to be devoid of a combination cooling and heating system functioning with any significant efficiency over longer periods of time. The current active cooling and heating systems, however, are too heavy, bulky, inefficient, and are effective for only a limited amount of time. These devices also consume too much power and use potentially dangerous materials such as lithium sulfur dioxide batteries or R134 a refrigerant. Passive cooling and heating systems use packets containing phase change chemicals, water or gel that require refrigeration, freezing or heating before use are not suitable to meet the needs of a user where refrigeration, freezing or heating of the passive cooling or heating components are unavailable such as in military field operations in hot, cold or combined hot and cold climatic conditions. The prior art active cooling and heating systems that have been developed, include:
While each of these prior art personal cooling and heating systems which fulfill their respective particular objectives and requirements, and are most likely quite functional for their intended purposes, it will be noticed that none of the prior art cited disclose an apparatus and/or method that is portable, rugged, and lightweight and that can be used in any orientation or used as a belt-mounted system, gas mask, bio-hazard suit or a backpack, to meet the operational requirements of the user. Also, the prior art cannot provide several continuous hours of operation without the burden of carrying the extra weight of cooling liquids and the additional garments that in actuality only exacerbate the thermal demands of a user.
As such, there apparently still exists the need for new and improved personal cooling and heating system to maximize the benefits to the user and minimize the risks of injury from its use. The current invention addresses all of these issues to provide a technology that provides a much more effective, efficient and user friendly system that does not require additional thermal burden of additional garments and carrying the weight of cooling liquids.
The current invention takes advantage of the thermally high efficient surface area of the human lungs to control the body's core temperature by providing chilled or heated air directly to the user's lungs by the user's own breath. The pulmonary system then further regulates the body's core temperature by cooling or heating, as the case may be, the blood carried through the body after passing through the lungs and receiving the heated or cooled air. The coefficient of thermal conductivity from a cooling or heating source to air is among the highest known and the heat exchange surface area of the human lung is on average 900 ft2, thereby minimizing, if not eliminating, thermal waste. The lungs surface itself is wet which results in a 100% absorption of any heat or cooled air temperature differential in the air contained in a user's breath by convection and evaporation.
In this respect, the present invention disclosed herein substantially corrects these problems and fulfills the need for such a device.
In view of the foregoing limitations inherent in the known types of personal cooling and heating systems now present in the prior art, the present invention provides an apparatus that has been designed to provide the following features for a user:
These features are improvements which are patently distinct over similar devices and methods which may already be patented or commercially available. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide a field designed apparatus and method of manufacture that incorporates the present invention. There are many additional novel features directed to solving problems not addressed in the prior art.
To attain this the present invention generally comprises six major components: 1) A user interface whereby when a user draws a breath while this invention is in use the inspiratory air comes principally from the device; 2) A housing connected to the user interface; 3) A cooling means contained within the housing such that when a user draws a breath the drawn air is thereby drawn into the housing where it is cooled prior to its exiting the housing through the user interface thereafter entering the user's body and ultimately being drawn into the lungs; 4) A heating means contained within the housing such that when a user draws a breath the drawn air is thereby drawn into the housing where it is heated prior to its exiting the housing through the user interface thereafter entering the user's body and ultimately being drawn into the lungs; 5) A control means to regulate the cooling means and the heating means; and 6) A valve means to prevent expired air from entering the housing.
These together with other objects of the invention, along with the various features of novelty which characterize the invention, will be pointed out with particularity in the claims which will be annexed to and forming a part of the full patent application once filed. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.
With reference now to the drawings, and in particular to
Any actual dimensions listed are those of the preferred embodiment. Actual dimensions or exact hardware details and means may vary in a final product or most preferred embodiment and should be considered means for so as not to narrow the claims of the patent.
List and Description of component parts of the invention:
The Pulmonary Body Core Cooling and Heating System has four main components:
In the Preferred Embodiment as depicted in FIGS. 1,2 and 3 the Cooling Unit (CU) is comprised of eight Reversible Thermoelectric Cooler (TEC) Modules (1) attached to the Temperature Exchange Module (11) such that the cold side of the eight Reversible Thermoelectric Cooler (TEC) Modules (1) thereby chill the Temperature Exchange Module (11) with the hot side of the eight Reversible Thermoelectric Cooler (TEC) Modules (1) each has a corresponding Cooling Fin (15) attached thereto to act as a heat sink to draw the heat away from the Reversible Thermoelectric Cooler (TEC) Modules (1); the eight Cooling Fins (15) are further aided in disbursing heat by the four Cooling Fans (13) which is activated by the Micro Controller (16) that is electrically and/or electronically connected to internal Temperature Sensors (3) in the Temperature Exchange Module (11) and the Air Exhaust Port (18).
In the Preferred Embodiment as depicted in
In the Preferred Embodiment as depicted in FIGS. 1,2 and 3 the Battery (7) for both the Cooling and Heating Units are generally off-the-shelf, rechargeable Lithium Ion batteries.
In the Preferred Embodiment as depicted in FIGS. 1,2 and 3 the system will be used with a Gas Mask (21) to provide a relatively air tight connection between the Portable Pulmonary Body Core Cooling and Heating System (40) and the user. The Air Exhaust Port (18) contains at least one Temperature Sensor (3) unit that monitors the temperature of the exhausted air that leaves a user's lungs and body after taking a breath and send this information to the Micro Controller (16) where it automatically processes and calculates the user's body core temperature and automatically adjusts the cooling and/or heating of the device to meet the demands of the user to maintain the user's core body temperature within normal range.
As depicted in
As depicted in
It would be obvious to one skilled in the art to use fuels such as odorless, clean-burning, non-smoking liquid fuels such as liquid benzine, pure white gasoline or lighter fluid as a replacement for the Electric Heating Strip (8) and/or the Reversible Thermoelectric Cooler (TEC) Modules (1). The burner would be installed externally. The drawbacks of using the burner are that the user would be required to carry a flammable liquid, would have to light the burner to ignite it. It would be possible to design a burner with an electronic ignition and controls that would not require the user to manually light it or shut it off. This type of design would provide the most heat for the weight of the system but would potentially be very dangerous for use in such activities as flight line maintenance since they are typically working in proximity to aircraft fuel vapors.
While my above descriptions of the invention, its parts, and operations contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of present embodiments thereof. Many other variations are possible, for example, other embodiments, shapes, and sizes of the device can be constructed and designed to work by the principles of the present invention; various materials, colors and configurations can be employed in the device's design that would provide interesting embodiment differences to users. The power supply to the unit may also be photovoltaic, as well as many other obvious variations. There are many different means of cooling from the use of ice, liquid nitrogen, dry ice, external cool or cold ambient air to standard compressed refrigeration techniques and many others that would all be obvious cooling means.
It would also be obvious to use some other means of connecting the device to the user such as a mouthpiece or a helmet such as in a bio-hazard outfit.
Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the claims and their legal equivalents as filed herewith.
| Number | Date | Country | |
|---|---|---|---|
| 60903202 | Feb 2007 | US |
