Abstract:
A method of purging air that includes sensing a first physical property within an enclosed volume of space, sensing a second physical property outside of the enclosed volume of space, calculating a difference between the first and second physical properties; and conveying air out of the enclosed volume of the space if the difference is greater than or equal to a predetermined value.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a system for purging air from an enclosed volume of space, such as the interior of a vehicle. 
     2. Discussion of Related Art 
     It is a well-known phenomenon that the cabin of a vehicle, such as an automobile, is often subjected to an abnormal increase in temperature when the vehicle is turned off and is standing under the scorching heat of the sun. Under hot soak conditions caused by high temperatures and sun load, the average temperature of the vehicle can increase by as much as 50 to 60° F. above the outside or ambient temperature. The increase in temperature lengthens the amount of time to comfort the occupants of the vehicle at the time of start up of the vehicle. In addition, when the vehicle has been exposed to hot soak conditions for long periods of time, such as several hours, the seats and interior of the vehicle become thoroughly heated to the higher temperature and, thus, increase the amount of time for reaching a level of comfort for the occupants. 
     One prior attempt at decreasing the amount of time for reaching a level of comfort for the occupants, is to use a pair of blowers that are powered by a solar panel. The blowers purge the hot air within the interior of the vehicle beginning from the time that the vehicle is turned off. Powering the blowers with a solar panel conserves the energy of the vehicle&#39;s battery used to start the vehicle. One disadvantage of this system is that it requires additional components than those that are normally available for a commercial vehicle. The additional components result in a more expensive and complicated vehicle. 
     It is also well known in the art that purging air from within the interior of a vehicle can be performed to improve the operation of so called electronic automatic temperature control (“EATC”) systems. Such EATC systems measure the temperature of the interior of a vehicle. The measured temperature is used by the EATC system to activate subsystems, such as ventilation mode, recirculation door positions, blower speeds and refrigeration cycles, which will lower or raise the interior compartment temperature to meet passenger expectations. Relevant subsystems of the EATC system include ventilation mode, recirculation door positions, blower speeds and refrigeration cycles. 
     Typically, a sensor or thermosistor measures the temperature of the interior compartment of the vehicle. Before the interior compartment temperature may be accurately measured, air in the immediate area of the sensor must be purged in favor of air pulled in from the interior compartment. 
     With regard to conventional EATC systems, purging does not typically begin until after the EATC is activated, which occurs after the ignition system of the vehicle is activated. However, it has been suggested to start the purging process before passengers are inside the vehicle and before the vehicle&#39;s EATC system is actually started, so that more accurate temperature readings may be made. 
     One disadvantage of the above-described systems is that they require separate power supplies for the purge system that are separate from the battery of the vehicle which results in an increase in the cost and complexity of a purge system. 
     In view of the above-described disadvantage, it is an object of the present invention to provide an improved temperature control device for the interior of a vehicle. 
     It is another object of the present invention to reduce the amount of discomfort an individual feels when entering a vehicle that has been exposed to the sun and/or heat. 
     It is another object of the present invention is to provide an air purge system that can safely be run off of a vehicle&#39;s battery during the time period that a vehicle is turned off. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention regards an air purge system that includes a first sensor for sensing a first physical property within an enclosed volume of space and a second sensor for sensing a second physical property outside of the enclosed volume of space. A blower is in fluid contact with both the enclosed volume of space and outside of the enclosed volume of space. A processor connected to the first and second sensors and the blower, wherein the processor calculates a difference between the first and second physical properties and activates the blower if the difference is greater than or equal to a predetermined value. 
     A second aspect of the present invention regards a method of purging air that includes sensing a first physical property within an enclosed volume of space, sensing a second physical property outside of the enclosed volume of space, calculating a difference between the first and second physical properties; and conveying air out of the enclosed volume of the space if the difference is greater than or equal to a predetermined value. 
     A third aspect of the present invention regards an air purge system that includes a blower that is in fluid contact with both an enclosed volume of space and outside of the enclosed volume of space, a power supply connected to the blower and a processor connected to the first and second sensors, the blower and the power supply; wherein the processor activates the blower and senses the power level of the power supply and deactivates the blower should the power level fall below a predetermined power level. 
     A fourth aspect of the present invention regards a method of purging air that includes activating a blower so as to convey air from an enclosed volume of space to outside of the enclosed volume of space, sensing a power level of a power supply connected to the blower and deactivating the power supply should the sensed power level fall below a predetermined power level. 
     Each of the above aspects of the present invention provides the advantage of decreasing the cost and complexity of a purge system. 
     The above third and fourth aspects of the present invention provide the advantage running a purge system off of the battery used to start a vehicle. 
     The present invention, together with attendant objects and advantages, will be best understood with reference to the detailed description below in connection with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically shows an air purge system according to the present invention; 
     FIG. 2 schematically shows a perspective view of a vehicle employing the air purge system of FIG. 1 according to the present invention; and 
     FIG. 3 shows a flow chart demonstrating a mode operating the air purge systems of FIGS.  1  and  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, FIG. 1 shows an embodiment of an air purge system  10  includes an internal and external air change-over damper  12  that is movable from a first position A, that allows for the circulation of internal air within the enclosed interior volume of space  14  of the interior of a vehicle  16 , to a second position B, that allows for the interior volume of space  14  of the interior of the vehicle  16  to be in fluid communication with the ambient atmosphere  18  outside the interior of the vehicle  16 . The damper  12  is moved from position A to position B and vice versa via a stepper motor  20  in a manner described below. As shown in FIG. 1, the damper  12  is located in a channel or duct  22  that has an opening  24  that is in fluid communication with the ambient atmosphere  18 . The channel or duct  22  has another opening  26  that is in fluid communication with the interior volume of space  14  of the interior of the vehicle  16 . 
     A blower  28  and a cooling unit  30  are also located within the channel or duct  22  as shown in FIG.  1 . Thus, the blower  28  is in fluid contact with both the interior volume of space  14  and the ambient atmosphere  18  located outside the interior volume of space  14 . The damper  12  and the blower  28  are each connected to a power supply, such as battery  32 , and a processor or control circuit  34 . The battery  32  preferably is used to start and run various electrical components of the vehicle. 
     As shown in FIGS. 1 and 2, an interior sensor  36  for determining a physical property, such as the temperature, of the interior volume of space  14  and an exterior sensor  38  for determining a physical property, such as the temperature, of the ambient atmosphere  18  are each connected to the processor  34 . 
     A mode of operation of the air purge system  10  is shown in the flow chart of FIG.  3 . In operation, the air purge system  10  is enabled upon determining whether the ignition of the vehicle has been turned off, per step  100  of FIG.  3 . This causes a switch  40  to close which results in the battery  32  being connected to processor  34  of the air purge system  10 . Once powered by the battery  32 , the processor  34  determines whether the power level of the battery  32  is about to fall below a predetermined power level, P, which is necessary to safely start the vehicle  20  with the battery  32 , per step  101 . If it is, then the air purge process is discontinued and the process returns to step  100 . If it is not, then the control circuit monitors the temperature of the ambient atmosphere  18  via sensor  38  per step  102 . 
     Should the sensor  38  determine that the temperature of the ambient atmosphere is below a predetermined value T ambient , such as 80° F., then the process returns to step  100 . Should the sensor  38  determine that the temperature of the ambient atmosphere  18  is at or above the predetermined value T ambient , then the processor  34  will monitor the temperatures of both the interior volume of space  14  and the ambient atmosphere  18  via temperature sensors  36  and  38 , respectively, per step  104  and  106 . Monitoring of the two temperatures will take place at a specific interval of time, such as once every hour. 
     While the processor  34  monitors the two temperatures, the processor calculates the difference between the two temperature readings by subtracting the temperature reading of sensor  38  from the temperature reading of sensor  36 , per step  108 . Should the calculated difference be less than a predetermined value Δ, such as 15° F., then the process returns to step  100 . Should the calculated difference be greater than or equal to the predetermined value Δ, then the processor  34  determines the position of the damper  12 , per steps  110  and  112 . If the damper is at position A, then the processor  34  activates the stepper motor  20  so as to move the damper  12  to position B, per step  114 . 
     Once the processor  34  determines that the damper  12  is at position B, the processor  34  closes a switch  42  that results in the battery  32  powering the blower  28 , per step  116 . The blower  28  is turned on for a predetermined amount of time, such as one minute. Activation of the blower  28  causes the hot air present in the interior volume of space  14  to be removed/purged and expelled into the ambient atmosphere  18 . After the predetermined amount of time, the process returns to step  100 . 
     The end result of the above process is that the interior of a vehicle that is shut off and subjected to sun soaked conditions is made more palatable to an individual who enters the interior. 
     The foregoing description is provided to illustrate the invention, and is not to be construed as a limitation. Numerous additions, substitutions and other changes can be made to the invention without departing from its scope as set forth in the appended claims.