Abstract:
An air conditioning unit includes a control that operates in an automatic air filtration mode of operation when commanded to do so. The control, when in this mode of operation, automatically activates an air filtration system within the unit in response to the sensing of contaminants in the air surrounding the unit. The automatic activation of the air filtration system occurs in response to an unfavorable comparison of a sensed value of air quality with an allowable limit for air quality. The allowable limit for air quality may be computed as a function of time so as to reduce the air quality required during times in which the space being heated or cooled is unoccupied.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to the control of an indoor air conditioning unit having an air filtration system within the unit.  
           [0002]    Indoor air conditioning units now include various air filtration systems which filter the air passing through the units. These air filtration systems typically require that at least a fan be activated so as to circulate air through a filter which removes impurities in the air such as dust, odors, or volatile chemical compounds. The filters that remove these impurities usually require some form of activation in order to perform their respective filtering capabilities. In the case of passive filters, this may only require the activation of a fan so as to circulate air through the filter. In the case of other types of filters such as electrostatic filters and photocatalytic filters, there may be a need to activate particular filtering mechanisms.  
           [0003]    It is desirable that any of the aforementioned filters be appropriately activated when the air quality in a room deteriorates. It is, however, not always possible to easily read the display of conditions measured by a unit so as to thereby activate air filtration. This may be especially true for an air conditioning unit mounted relatively high on a wall wherein a remote control is often used to read the conditions measured by the unit. It is also possible that an occupant of a room being heated or cooled by the air conditioning unit would not even react to poor air quality. In this regard, the occupant may be quite aware of comfort level such as temperature but not have any idea as to air quality level. Furthermore, the air filtration system may simply not be activated when the room or space is unoccupied. While this latter situation may be appropriate for unoccupied times, there will nonetheless be a period of time before the quality of air is brought to within allowable limits following occupancy and activation of the air filtration system within the unit.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention provides an air conditioning unit with an air filtration system that is automatically activated any time of the day or night when the measured air quality in a space drops below permissible limits. The around-the-clock air filtration capability is preferably an automatic mode of operation which may be selected when programming the operation of the unit. The air filtration system includes an air contaminant sensor preferably mounted within the unit in such a manner so as to be able to sense the air surrounding the unit. The air contaminant sensor is connected to a microprocessor control that has been programmed to periodically read the sensor so as to determine whether the air quality in the room has dropped to a level requiring the activation of one or more air filters in the unit. The thus activated air filters remain on until such time as the sensed contaminant level has reached a point where the air quality level is acceptable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    For a fuller understanding of the present invention, reference should now be made to the following detailed description taken in conjunction with the accompanying drawings wherein:  
         [0006]    [0006]FIG. 1 illustrates an indoor air conditioning unit which provides either heated or cooled air to a space in which the unit is mounted;  
         [0007]    [0007]FIG. 2 illustrates an air filter located within the air flow path of the unit in FIG. 1;  
         [0008]    [0008]FIG. 3 is a block diagram of a microprocessor control system within the unit of FIG. 1 that is connected to the filter of FIG. 2; and  
         [0009]    [0009]FIG. 4 is a flow chart of the process used by the processor of FIG. 3 so as to activate the filter of FIG. 2.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]    Referring to FIG. 1, an air conditioning unit  10  is seen to include an inlet  11  and an outlet  12  wherein air is brought in through the intake  11  and processed before exiting at the outlet  12 . The air may be filtered before exiting at the outlet  12  or it may be filtered in conjunction with being heated or cooled by the unit. It is to be appreciated that the air conditioning unit  10  may be a so called hi-wall unit mounted high on a wall within a room that is to be heated or cooled. Such units normally include a remote control  14  that is selectively activated by a person so as to communicate with a receiver  16  on the unit.  
         [0011]    Referring now to FIG. 2, an air contaminant sensor  20  is illustrated as being mounted near the air intake  11  of the air conditioning unit so as to thereby sense the degree or amount of contaminants in the air surrounding the unit. It is to be appreciated that the sensor may be mounted elsewhere either inside or outside of the unit  10 . The mounting must however be such as to assure that the sensor  20  measures contaminants present in the air that can be processed by the unit  10 . The air contaminant sensor may furthermore be any of a number of different types of sensors that measure anything from dust to other types of contaminants including odors or volatile chemical compounds.  
         [0012]    A fan  22  causes air to flow through an air filter  24  where it is filtered before being heated or cooled by coils such as  26  if heating or cooling is required. It is to be appreciated that the air filter  24  may be passive and not require any particular activation in order to filter the air. On the other hand, it may be a type of filter that requires specific activation. This would be true of certain types of electrostatic filters or photo catalytic filters.  
         [0013]    Referring now to FIG. 3, a processor  30  is illustrated as being connected to the receiver  16  and the contaminant sensor  20 . The processor is operative to send appropriate signals to a filter control  32  or a fan control  34  as may be required. In particular, the processor will be responsive to a particular mode selection received from the receiver  16  so as to thereafter analyze sensed measurements of contaminants in the air from the sensor  20 . The processor will activate the fan control  34  and if necessary the filter control  32  when the sensed measurements indicate that the same is required.  
         [0014]    Referring now to FIG. 4, a flow chart of the process executed by the processor  30  so as to send appropriate control signals to the fan control  34  and the filter control  32  is illustrated. The process begins with a step  40  wherein the processor inquires as to whether an automatic air filtration mode has been selected. It will be remembered that the processor  30  receives communications from the remote control  14  via the receiver  16 . In the event that the automatic air filtration mode has been selected by a person operating the remote control  14 , then the processor will proceed out of step  40  along the yes path to a step  42 . The processor will read the air contaminant sensor  20  in a step  42 . As has been previously noted, the air contaminant sensor can be any of a variety of sensors including a dust sensor or a more sophisticated sensor that detects other types of impurities in the air that may need to be filtered. In any event, the air contaminant sensor will produce a value that can be compared with an allowable or acceptable limit for the particular sensed value. This allowable limit is obtained by the processor in a step  44 . This limit may be a constant or a limit that varies with time. In the latter case, the processor will read the current time from a system clock associated with the processor and compute the allowable limit. The computation can itself be either a table look up of allowable air quality limits with respect to time or it may be an algorithmic formula. In any event, the processor proceeds from having obtained the allowable air quality limit in step  44  to step  46 . The processor inquires in step  46  as to whether the measured air quality as sensed in step  42  is outside the allowable limit obtained in step  44 . In the event that the sensed or measurement of contaminants is within allowable limits, then the microprocessor will proceed along the no path back to step  40 .  
         [0015]    Assuming however that the sensed measurement of contaminants is outside the allowable limit, then the processor will proceed out of step  46  to a step  48  and inquire as to whether the fan  22  is on. This will merely be a check of the fan control  34  to ascertain whether the fan is in fact on. In the event that the fan is not on, then the processor will proceed to step  50  and activate the fan control  34 .  
         [0016]    The processor will next proceed in a step  52  to activate the filter control  34  if the filter  24  within the unit requires such an activation. If the filter  24  does not require activation, then step  52  will not be necessary. Assuming however that the filter does require activation, than the processor  30  will do so in step  52 . For example, if the filter  24  is an electrostatic filter requiring the application of voltage thereto then the processor in step  52  will send a signal to the filter control  24  asking the filter control to apply the voltage to the electrostatic filter. The electrostatic filter will thereafter attract and filter contaminants such as dust in the air. On the other hand, if the filter  24  is for instance a photo catalytic type of filter requiring the activation of ultraviolet lamps, then the lamps and associated filter apparatus will be activated by the filter control  24  in response to the command from the processor  30  in step  52 .  
         [0017]    The processor proceeds from step  52  to again read the air contaminant sensor  20  in a step  54  before obtaining the allowable air quality limit in step  56 . The allowable limit may in fact change during the time that commanded air filtering is occurring. In this latter case, the allowable limit will be computed each time the processor executes step  56 . In any event, the processor proceeds to step  58  and determines whether the measured air quality is outside the allowable limit. In the event that air quality remains outside the allowable, the processor will proceed to step  60  wherein a time delay is introduced before returning to step  54 . It is to be appreciated that the time delay will be chosen so as to allow for a sufficient amount of time to elapse where air filtration can occur before reading the contaminant sensor  20  again in step  54 . The processor will again read the sensor  20  in step  54  , obtain the allowable limit in step  56  and thereafter determine whether air quality is outside the allowable limit in step  58 . Assuming that at some point in time the air filtration by the filter  24  will produce acceptable air quality, then the processor will proceed along the no path out of step  58  to a step  62  and eliminate fan demand required by the process of FIG. 4. It is to be appreciated that the elimination of fan demand by the process of FIG. 4 will not necessarily deactivate the fan  22 . In this regard, if there are other control requirements on the fan  22 , then elimination of fan demand in step  62  will not affect such other requirements. The processor proceeds from step  62  to step  64  and deactivates the filter control  32 . Any positive activation of any control associated with a particular filter  24  requiring activation will be turned off in step  64  in much the same manner as it was previously activated in step  52 . The processor proceeds from step  64  back to step  40  wherein the process of FIG. 4 will again be implemented as long as the automatic air filtration mode remains selected.  
         [0018]    It is to be appreciated that a preferred embodiment for an automatically activated indoor air filtration system within an air conditioning unit has been disclosed. The automatic mode of operation occurs independently of any other operations that may be required of the air conditioning unit such as heating or cooling. Alterations and modifications to the thus disclosed system may occur without departing from the scope of the invention. Accordingly, the foregoing description of the preferred embodiment is to be limited only by the following claims and equivalents thereto.