Abstract:
A method and system for climate control uses a desiccant in an automobile. The desiccant removes humidity or moisture from air passing through the ventilation system. The desiccant is recharged or dried by application of a vacuum. The lower pressure generated by the vacuum reduces the temperature at which water evaporates or boils off of the desiccant material.

Description:
BACKGROUND 
     This invention relates to dehumidification in an enclosed area. In particular, a method and system for climate control using a desiccant in an automobile is provided. 
     Humidity in automobiles condenses on windows, impairing a vehicle operator&#39;s vision. For lower temperatures with high humidity, the typical ventilation system in an automobile may be incapable of effectively, efficiently or quickly removing the condensation. For example, air is recirculated from within a passenger compartment. Recirculating the air delays or prevents removal of the condensation from the window. 
     Desiccant systems have been developed for use in busses. Desiccants absorb a limited amount of moisture. Once the limited amount of moisture has been absorbed, the desiccant is dried or recharged by application of heat. The desiccant is exposed to exhaust gases from the engine. However, it is undesirable to route exhaust gases adjacent to the air duct or ventilation system of the bus. The proximity and connection between the exhaust gases and the air ducts for ventilation may allow leakage of exhaust into the passenger compartment. Furthermore, the exhaust gases can foul or otherwise deteriorate the desiccant material. 
     BRIEF SUMMARY 
     The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiment described below includes a method and system for climate control using a desiccant in an automobile. 
     A desiccant removes humidity or moisture from air passing through the ventilation system. The desiccant is recharged or dried by application of a vacuum. The lower pressure generated by the vacuum reduces the temperature at which water evaporates or boils off of the desiccant material. 
     In one aspect, a method and system for climate control of a desiccant in an automobile are provided. A desiccant is exposed to air within an automobile. A vacuum source is operative to generate a low pressure area adjacent to at least a portion of the desiccant. 
     In another aspect, a system for climate control using a desiccant in an automobile is provided. The system includes an air duct and a vacuum chamber. A desiccant is positionable within the air duct and the vacuum chamber. An actuator operatively connects with the desiccant. The position of the desiccant relative to the air duct in the vacuum chamber is responsive to the actuator. A controller connects with the actuator. 
     Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a diagram of one embodiment of a system for climate control using desiccant. 
     FIG. 2 is a diagram of another embodiment of a system for climate control using a desiccant. 
     FIG. 3 is a flow chart diagram representing one embodiment of the operation of the system of FIG.  2 . 
     FIG. 4 is a perspective view of a system for climate control using a desiccant of yet another embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments discussed below use a vacuum or low pressure to recharge a desiccant. The humidity or moisture absorbed by the desiccant is removed by evaporation due to the low pressure. The desiccant is repetitively used to remove humidity or moisture from the air in the passenger compartment of an automobile. When air is recirculated within the passenger compartment through the ventilation system in high humidity and lower temperature environments, the desiccant removes humidity. The drier air within the passenger compartment does not allow formation of condensation on windows. The system also allows use of recirculating air for faster warming up of the vehicle during particularly low temperature environments. The system may decrease the load on an air conditioning system in a higher temperature environments. 
     FIG. 1 shows one embodiment of a system for climate control using a desiccant. A desiccant  10  is provided in or adjacent to an air duct  12  and a vacuum chamber  14 . The air duct  12  comprises a metallic, plastic or other tube or chamber of air. The air duct  12  is shaped as a tube, cylinder, rectangular or square shaped tube or any other geometric body for the transport of air. The air duct  12  may be of any of various sizes. The air duct  12  connects with a passenger compartment of an automobile in one embodiment. For example, the air duct  12  comprises a return air duct of an air handling case in an automobile. As yet another example, the air duct  12  comprises an air intake inlet or vent of the return air duct behind or below a dashboard of an automobile. In alternative embodiments, the air duct  12  connects with other chambers, compartments or bodies of air where reduced humidity is desired. 
     The desiccant  10  comprises a silica-based desiccant cartridge. In alternative embodiments, the desiccant comprises a zeolite, clay base or salt base desiccant. One to two pounds or other amounts of silica desiccant material are placed within a plastic or metallic cartridge allowing exposure of the desiccant  10  to air. The desiccant  10  is shaped in any of various shapes, such as a rectangular or circular volume. The desiccant  10  is sized such that it fits within or adjacent to the air duct  12 , impeding none, a portion or the entire air duct  12 . 
     Additional material may be provided with the desiccant  10 . For example, activated carbon is incorporated within the desiccant material  10  or adjacent to the desiccant  10 . Activated carbon reduces odors within the air traveling through or near the desiccant  10 . Alternatively or additionally, a biocide, such as antifungal or antimold material, is included with or adjacent to the desiccant material  10 . Other air purifying or conditioning materials may be used. 
     The vacuum chamber  14  comprises a vacuum source. The vacuum chamber  14  comprises a volume of various shapes and sizes, such as a generally rectangular volume sized to include at least a portion of the desiccant  10 . The vacuum chamber  14  may be larger than the volume needed to house the desiccant material  10 . The vacuum chamber  14  is formed from plastic, metal or other material able to withstand a lower pressure without collapse. 
     The vacuum chamber  14  has a low pressure. One or more of various mechanisms may be used for generating the low pressure. For example, the engine vacuum generated by an engine of an automobile is used to create the low pressure within the vacuum chamber  14 . As another example, the Bernoulli affect is used to generate a vacuum within the vacuum chamber  14 . The flow of fluid within the automobile is used to generate a suction, resulting in a vacuum. In one embodiment, a hose connects the vacuum chamber  14  to an engine coolant hose. The flow of engine coolant creates a suction within the vacuum chamber  14 . 
     Water within the desiccant  10  in or adjacent to the vacuum chamber  14  is boiled or evaporated from the desiccant  10 . The recharged desiccant  10  is exposed to air in the passenger compartment, allowing the recirculation of air within an automobile without excessive fogging on windows and reducing the load on an air conditioning system by removing latent heat from the air. The passive desiccant  10  reduces the power consumption of a climate control system within an interior of an automobile in high humidity environments. 
     As shown, the desiccant  10  is within both the vacuum chamber  14  and the air duct  12 . In one embodiment, the desiccant  10  is moveable between or within each location. The desiccant  10  may be positioned adjacent to one or both the air duct  12  and the vacuum chamber  12 . The desiccant  10  may be fixedly mounted in alternative embodiments. 
     FIG. 2 shows one embodiment of a system for climate control using a desiccant in an automobile. The system includes a desiccant cartridge  20 , first and second vacuum chambers  22 ,  24 , an air duct  26 , a vacuum tube  28 , a vacuum source  30 , an actuator  32 , a controller  34 , a temperature sensor  36  and a humidity sensor  38 . In response to control signals from the controller  34 , the actuator  32  acts to move portions of the desiccant cartridge  20  into the air duct  26  and other portions into one of the vacuum chambers  22 ,  24 . Continuous or substantially continuous removal of humidity from air within the air duct  26  is provided. The air duct  26 , desiccant cartridge  20  and the vacuum chambers  22 ,  24  comprise the same or similar materials, shapes, and sizes discussed above with respect to FIG.  1 . 
     The desiccant cartridge  20  is segmented. A wall or barrier  40  separates the desiccant cartridge  20  into at least two portions. The barrier  40  of one embodiment separates the desiccant cartridge  20  in half. The barrier  40  is positioned such that a seal or partial seal is provided to separate a portion of a desiccant cartridge  20  within a vacuum chamber  22 ,  24  from the portion of the desiccant cartridge  20  within the air duct  26 . In the dual vacuum chamber embodiment shown in FIG. 2, the ends of the desiccant cartridge  20  are also shaped so as to provide a seal or partial seal between the vacuum chambers  22 ,  24  and the air duct  26 . The desiccant cartridge  20  comprises a metal, plastic or other material in a web (i.e., screen) or partial web-partial enclosure for exposing desiccant to air. 
     The desiccant cartridge  20  is mounted within slots or apertures within the vacuum chambers  22  and  24 . In one embodiment, rails or other guiding mechanisms are additionally provided to guide the desiccant cartridge  20  as it is positioned within the vacuum chambers  22 ,  24  and the air duct  26 . Rollers may also be provided for positioning the desiccant cartridge  20 . 
     Two vacuum chambers  22 ,  24  are provided so that while one portion of the desiccant cartridge  20  is within the air duct  26 , the other portion is exposed to the low pressure within one of the vacuum chambers  22 ,  24 . When the desiccant cartridge  20  is repositioned, the recharged portion of the desiccant cartridge  20  is exposed within the air duct  26  and the portion of the desiccant cartridge  20  storing more water is positioned in the associated vacuum chamber  22 ,  24 . For example, a left or first half of a desiccant cartridge  20  is positionable within a first vacuum chamber  22  and the air duct  26 . A right or second half of the desiccant cartridge  20  is positionable within the air duct  26  and a second vacuum chamber  24 . The portion of the desiccant cartridge  20  exposed within the air duct  26  is switched from one portion to the other of the desiccant cartridge  20 . In alternative embodiments, a wheel structure is used for the desiccant cartridge  20  and a single vacuum chamber  22 ,  24  are provided. The desiccant cartridge  20  is recharged by rotating the portion of the desiccant cartridge  20  exposed within the air duct  26  into the vacuum chamber  22 . In other alternative embodiments, different structures and different numbers of associated vacuum chambers may be provided. 
     The vacuum source  30  is connected through the vacuum hose  28  to the vacuum chambers  22  and  24 . The same or different sources of vacuum  30  may be used for each of the vacuum chambers  22 ,  24 . In one embodiment, the vacuum source  30  comprises a fluid pump, such as provided in a coolant system. A portion of the vacuum hose  28  comprises a hose for carrying engine coolant. An additional hose is connected to the coolant hose for generating a suction with the Bernoulli effect for the vacuum chambers  22  and  24 . For example, a T connection is used. In an alternative embodiment, the vacuum source  30  comprises an engine vacuum or an auxiliary belt or electric powered vacuum pump. For example, an auxiliary electrically powered vacuum pump is provided in the engine compartment of the automobile. The vacuum hose  28  communicates a suction or low pressure to the vacuum chambers  22 ,  24 . In alternative embodiments, the vacuum source  30  connects directly to or is within the vacuum chambers  22 ,  24 . 
     The vacuum hose  28  comprises a rubber, plastic, fiber, metal, combinations thereof or other material for transmitting liquid or gas, such as air, to generate suction. 
     Where the Bernoulli effect is used, a degasser or other device for removing air sucked into the flowing fluid to create the low pressure is preferably provided. For example, coolant systems within automobiles typically have a degasser. 
     The actuator  32  comprises an electric motor with a push rod assembly. The actuator  32  is electrically activated to move the rod and connected desiccant cartridge  20 . Alternatively, an actuator with an associated gear, pulley or belt system is used for repositioning or switching the desiccant cartridge  20 . The actuator  32  is positioned within or adjacent to a vacuum chamber  24 , the air duct  26  or another location. The actuator  32  is positioned such that the desiccant cartridge  20  switchably recharges and exposes recharged desiccant within the air duct  26 . The actuator  32  may alternatively directly connect with the cartridge  20 . In alternative embodiments, hydraulic, vacuum operated, or non-electric actuator devices are used for positioning the desiccant cartridge  20 . 
     A controller  34  controls operation of the actuator  32 . The controller  34  comprises an application specific integrated circuit, a digital signal processor, an analog circuit, a general processor, combinations thereof or other device for receiving inputs and outputting control signals to the actuator  32 . In one embodiment, the controller  34  comprises a multifunction processor used for other control within the automobile. 
     The controller  34  receives inputs from one or move devices. In one embodiment, the controller  34  receives inputs from the temperature sensor  36 , the humidity sensor  38 , and a recirculation control button  42 . Different, additional, or fewer inputs may be provided. The temperature sensor  36 , the humidity sensor  38 , and the recirculation control button  42  comprise any one or more of various sensors or buttons used in automobiles for climate control or other purposes for the operation of the automobile. For example, the temperature and humidity sensors  32 ,  38  used for automatic climate control are also used as input to the controller  34  for operation of the actuator  32 . The recirculation button  42  comprises a button, slide or other input device for the operator of the automobile to select recirculation of air within the ventilation system. 
     The controller  34  responds to the input from one or more devices, such as the temperature sensor  36 , the humidity sensor  38 , and the recirculation control button  42 . In response to the inputs, the controller  34  causes the actuator  32  to reposition the desiccant cartridge  20 . In one embodiment where the climate control system is set to recirculate air within the passenger compartment, the controller monitors the temperature and humidity from the temperature sensor  36  and humidity sensor  38 . Where a threshold level of humidity and a threshold lower temperature is detected, the controller  34  causes the actuator to position a recharged portion of the desiccant cartridge  20  within or adjacent to the air duct  26 . The controller  34  then periodically repositions the desiccant cartridge  20  or, after a predetermined time, monitors the environment as discussed above until another reposition is triggered. 
     Repositioning of the desiccant cartridge  20  after a time or periodically continues until the climate control system is removed from a recirculation mode, the temperature exceeds a threshold, the humidity  38  becomes sufficiently low, an air conditioning compressor turns on, another event occurs or combinations thereof. Depending on the desiccant, an amount of wator vapor that is about 20-50% of the dry weight of the desiccant may be absorbed. For example, two to three hours are used to absorb water vapor after one reposition of the desiccant cartridge  20 . It is estimated that one hour is needed for recharging, but this time may differ as a function of various factors including the amount of vacuum. 
     In other embodiments, the controller  34  also controls the vacuum source  30 . For example, the controller  34  turns the vacuum source  30  on or off in conjunction with actuation of the actuator  32  and continued periodic actuation. In yet other alternative embodiments, the controller  34  operates valves or switches to control the supply of low pressure to the vacuum chambers  22  and  24 . 
     FIG. 3 shows a flow chart of one embodiment representing the operation of the climate control system of FIG.  2 . The flow chart represents one embodiment for exposing a desiccant to air within the passenger compartment and a generating a low pressure to remove liquid from the desiccant. In act  50 , selection of a recirculation setting is detected. In act  52 , a temperature within the passenger is detected. In act  54 , the humidity within the passenger compartment is detected. In alternative embodiments, any one or more of act  50 ,  52 , or  54  may be skipped. In response to activation of the recirculation setting, a range of temperatures and range of humidities, a vacuum is applied to the desiccant material. In act  56 , application of the low pressure by activating a pump, generating a Bernoulli effect, or positioning a portion of a desiccant material within a vacuum chamber removes liquid from the desiccant material. To further remove humidity from air within the passenger compartment, the desiccant material is shifted to expose recharged desiccant within the air in communication with the passenger compartment in act  58 . For example, silica desiccant material is exposed to air within an air duct while another portion of a desiccant material is exposed to a low pressure vacuum. Other filtering may be provided in act  58 , such as providing for carbon activated filtering. Periodically as a function of time, detected environmental conditions, or other inputs, the desiccant material is shifted in act  58  so that recharged desiccant is exposed to air associated with the passenger compartment and other portions of the desiccant material are exposed to a low pressure for recharging the desiccant. 
     FIG. 4 is a perspective view of another embodiment of the climate control system  60 . The climate control system includes a desiccant system  62  and an air handling unit  64 . The air handling unit  64  is adapted for mounting behind a dash board of an automobile. The air handling unit  64  provides heated, cooled and/or filtered air to the passenger compartment. 
     The air handling unit includes an inlet duct or vent  66 . The inlet vent  66  is adapted for drawing air from the passenger compartment in to the air handling unit  64 . 
     The desiccant system  62  connects to the inlet vent  66 . In one embodiment, the desiccant system  62  covers the inlet vent  66 . The desiccant system  62  comprises a housing  68  and two nipples  70 . The housing  68  comprises metal, plastic, other materials or combinations thereof The housing  68  contains two vacuum chambers and an air flow or air duct section as described above with reference to FIG.  2 . The air flow section allows air to pass from the passenger compartment, through the housing  68  and into the inlet vent  66 . 
     In the embodiment shown, each vacuum chamber is associated with one of the nipples  70 . The vacuum from the vacuum source is provided through the nipples  70 . The desiccant is about ⅔ the length of the housing  68 . The desiccant slides between 1) exposing a first half in the air flow section and placing a second half in one of the vacuum chambers and 2) exposing the second half in the air flow section and placing the first half in the other vacuum chamber. 
     While the invention has been described above by reference to various embodiments, it will be understood that many changes and modifications can be made without departing from the scope of the invention. For example, any of various sources of vacuum and desiccant materials may be used, whether now known or later developed. Additionally, different relative sizes and shapes of various components of the climate control system may be used. 
     It is therefore intended that the foregoing detailed descriptions be understood as an illustration of the presently preferred embodiments of the invention, and not as a definition of the invention. It is only the following claims, including all equivalents, that are intended to define the scope of this invention.