Abstract:
An airflow proving device is provided. The device includes: a housing defining an airflow pathway; a first chamber within the housing; a second chamber within the housing located downstream in the flow pathway from the first chamber; structure in the housing defining an orifice, the orifice providing fluid communication between the first and second chamber and being part of the fluid pathway; and a pressure measuring device having a first sensor configured to monitor a pressure in the first chamber and a second sensor configured to monitor a pressure in the second chamber.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The present disclosure relates generally to an apparatus and method for confirming airflow through a pathway. More particularly, the present invention relates to an apparatus and method for confirming airflow through a system that includes a combustion device. 
       BACKGROUND OF THE INVENTION 
       [0002]    Combustion systems such as boilers, furnaces or any other commercial or household combustion system rely on air flowing through the system to assure proper combustion at the burner. Good and reliable flow of air through the system aids to provide complete combustion of the fuel. Manufacturers of equipment which utilize combustion as an energy source are continuing to increase the turndown ratio of that equipment. The turndown ratio is the ratio of the minimum and maximum input rate of a particular unit. What may be input may be air, fuel, or a combination of an air-fuel mixture. 
         [0003]    As the minimum input rate decreases, the ability to accurately control the combustion process may become increasingly difficult. When certain conditions present themselves, for example, blocked combustion air, blocked exhaust pipes, or wind conditions at the vent termination unit may cause the combustion process to lose stability or efficiency. This loss in combustion may create incomplete combustion which can create large amounts of carbon monoxide or even loss of flame. These and other undesirable conditions may be the result of a lack of airflow through the combustion system. As a result, it can be difficult to ensure that at least a minimal amount of air is, in fact, flowing through the combustion system. 
         [0004]    Relying on a setting for a blower to provide accurate information regarding flow of air through the system may be problematic. Blowers will tend to run and perhaps even increase in speed when there are blockages of airflow through the system. As a result, while the blower speed may provide a good approximation of airflow during ideal conditions, blower speed does not always provide a reliable indication of airflow during adverse conditions such as, for example, but not limited to, blockages in the airflow path or wind conditions at the vent termination unit. As a result, reliance on the blower speed alone does not confirm an amount of air flowing through the system. 
         [0005]    Accordingly, it is desirable to provide a method and apparatus that may provide a more reliable indication of air flowing through the system and specifically, confirmation of a minimum of input air flowing through the system. 
       SUMMARY OF THE INVENTION 
       [0006]    The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments a method and apparatus may provide a more reliable indication of air flowing through the system and specifically, confirmation of a minimum of input air flowing through the system. 
         [0007]    In accordance with one embodiment of the present invention, an airflow proving device is provided. The device includes: a housing defining an airflow pathway; a first chamber within the housing; a second chamber within the housing located downstream in the flow pathway from the first chamber; structure in the housing defining an orifice, the orifice providing fluid communication between the first and second chamber and being part of the fluid pathway; and a pressure measuring device having a first sensor configured to monitor a pressure in the first chamber and a second sensor configured to monitor a pressure in the second chamber. 
         [0008]    In accordance with another embodiment of the present invention, a method for confirming airflow is provided. The method includes: configuring air to flow between a first chamber and a second chamber through an orifice; measuring an air pressure associated with the first chamber; measuring an air pressure associated with the second chamber; comparing the two measured pressures against a threshold; and adjusting a speed associated with the blower depending upon the difference between the air pressure associated with the first chamber and the air pressure associated with the second chamber falls below the threshold. 
         [0009]    In accordance with yet another embodiment of the present invention, an airflow proving device is provided. The device may include: means for defining an airflow pathway; a first chamber within the housing; a second chamber within the housing located downstream in the flow pathway from the first chamber; means for defining an orifice, the orifice providing fluid communication between the first and second chamber and being part of the fluid pathway; and means for comparing measuring pressure having a first means for sensing a pressure in the first chamber, and a second means for sensing pressure associated with the second chamber. 
         [0010]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0011]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0012]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a schematic diagram of a combustion system incorporating a minimum input air proving device in accordance with the disclosure. 
           [0014]      FIG. 2  is a schematic, cross-sectional view of a minimum input air proving device in accordance with the disclosure. 
           [0015]      FIG. 3  is a flowchart outlining steps for accomplishing a method of controlling a combustion system that includes confirming an amount of air flowing through the system in accordance with the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present disclosure provides a method and apparatus for determining or verifying that there is at least a minimal airflow through the system. 
         [0017]    A combustion system  10  is shown in  FIG. 1 . The combustion system  10  includes a controller  12  operably connected to various components in the system  10 . An airflow proving device  14  in accordance with this disclosure is mounted in an initial portion of an air pathway. The air flow proving device  14  includes a pressure measuring device  15 . The airflow proving device  14  has an air inlet  16  and an air outlet  18 . Airflow is represented by arrows A through the system  10 . Air flows through the air inlet  16  through the airflow proving device  14  and out the air outlet  18 . The air pathway continues through the airflow proving device  14  through a conduit  20  into the inlet  22  of an air/fuel mixture device  24 . In the air/fuel mixture device  24 , fuel is combined with the air flowing through the airflow pathway. In some embodiments, the air and fuel mixing may occur via a venturi-type system. In other embodiments other ways of mixing the air and fuel together may occur in accordance with this disclosure. 
         [0018]    After the air and fuel have mixed in the air/fuel mixture device  24 , the air/fuel mixture will flow through the outlet  26  through the conduit  28  into the inlet  30  of the blower  32 . The blower  32  moves the air and/or air/fuel mixture through the system  10 . The after the air/fuel mixture flows to the blower  32  it flows out of the outlet  34  into the conduit  36  and into the inlet  38  of the combustion device  42 . Once the air/fuel mixture is in the combustion device  42 , it will combust as controlled by the combustion device  42 . After combustion, the exhaust gases will flow out of the outlet  40  and through the exhaust system  41 . 
         [0019]    In some embodiments, the combustion device  42  may be a furnace, a boiler, heater, or any other combustion device. While the examples set forth herein primarily discuss combustion used in domestic or commercial heat this disclosure may also be applicable to any type of combustion device. 
         [0020]      FIG. 2  is a close-up cutaway view of an air flow proving device in accordance with an embodiment. The airflow proving device  14  includes a wall  50  that defines an orifice  52 . The orifice  52  provides fluid communication between the inlet chamber  54  and the outlet chamber  56 . Air, as represented by arrow A, flows into the inlet  16  and into the inlet chamber  54 . The air continues to flow through the orifice  52  into the outlet chamber  56  out of the outlet  18  and into the conduit  20  and continues along the fluid pathway as illustrated and described with respect to  FIG. 1 . 
         [0021]    The pressure measuring device  15  has two leads  46  and  48 . The lead  46  is configured to sense a pressure associated with the air in the inlet chamber  54 . The lead  48  is configured to sense an air pressure associated with the outlet chamber  56 . In embodiments where the pressure measuring device  15  is simply a pressure switch, if a difference between the pressure sensed by leads  46  and  48  goes below a minimum threshold, then the pressure measuring device  15  will send a signal via connection  44  to the controller  12 . In this case, the pressure measuring device  15  acts like a pressure switch and trips if a minimum threshold is exceeded. 
         [0022]    In other embodiments, the pressure measuring device  15  acts as a pressure sensor and sends signals to the controller  12  via the connection  44  indicative of a difference in pressure detected by leads  46  and  48 . 
         [0023]    In some embodiments, if the orifice  52  is sized appropriately with respect to a desired airflow, as air flows through the airflow proving device  14  as represented by arrow A, the airflow will encounter a bottleneck at orifice  52 . This will cause pressure to decrease within chamber  56  in comparison to chamber  54 . If a lot of air is moving through the airflow proving device  14 , then there will be a large pressure difference between chambers  54  and  56 . This pressure difference will be a result of a vacuum in chamber  56  as a result of the bottleneck of air trying to flow through the orifice  52 . If no or little air is flowing through the airflow proving device  14  then the pressures between chambers  54  and  56 , as sensed or detected by the pressure measuring the device  15 , will approach or equal a zero difference in pressure. As a result, the higher difference in pressure detected by leads  46  and  48  will indicate higher airflow through the airflow proving device  14 . Thus, the pressure measuring device  15  can confirm by measuring different pressures within chambers  54  and  56 , whether air is flowing through the air proving device  14 . 
         [0024]    Returning to  FIG. 1 , in some embodiments, the controller  12  is connected via connections  44  to the pressure measuring device  15 , the air/fuel mixture device  24 , the blower  32 , and the combustion device  42 . In other embodiments, the controller  12  may be connected only to the pressure measuring device  15  and the blower  32 . In other embodiments the controller  12  may be connected to the pressure measuring device  15 , the blower  32 , and any other combination of elements within the system  10 . 
         [0025]    In some embodiments, the signals received by the controller  12  from the pressure measuring device  15  will allow the controller  12  to determine whether to speed up, slow down, maintain speed, or turn off the blower  32 . In other embodiments, feedback or signals received by the controller  12  from the pressure measuring device  15  may result in the controller  12  generating other control signals to other components of the system  10 . For example, depending on signals received by the controller  12  from the pressure measuring device  15 , the controller  12  may give control signals to the air/fuel mixture device  24 , the blower  32 , the combustion device  42 , or any combination of those elements. 
         [0026]    In some embodiments, the minimum threshold settings may be programmed by a user or set at the factory. These settings may remain fixed until the controller  12  is reprogrammed. In some embodiments, control settings or present conditions at various components such as the air/fuel mixture device  24 , the blower  32 , or the combustion device  42 , may result in the controller reacting differently to signals received from the pressure measuring device  15 . For example, if the blower  32  is set at a relatively slow speed causing air and/or air/fuel mixture to flow through the system  10  at a relatively slow pace, then the controller  12  will allow the blower  32  to operate without further signals from the controller to change operation of the blower  32  when signals from the pressure measuring device  15  indicate a relatively low airflow in the airflow proving device  14 . Thus, the threshold that the controller  12  uses to make decisions on whether to interfere with operation of other components within the system  10  may depend upon the current setting of those components. As a result, if, for example, the blower  32  is operating at a relatively high speed, then the controller  12  will demand a relatively high amount of air flow through the airflow proving device  14  as detected by the pressure monitoring device  15 , but if the blower  32  is operating at a relatively low speed, then the controller  12  will lower the threshold of detective air flowing through the air proving device  14  before interfering with operation blower  32  or any of the other components in the system  10 . One of ordinary skill in the art, after reviewing this disclosure, will understand what thresholds to program into the controller to achieve desired system performance. 
         [0027]      FIG. 3  illustrates an example method that may be accomplished by the system  10 . For example in step S 1 , the system  10  measures pressure. This can be accomplished by the pressure measuring device  15  sensing a difference in pressure within the chambers  54  and  56 . In step S 2 , the controller  12  may send a control signal to the blower  32 . This control signal may, in some embodiments, be to shut down the blower  32 . In other embodiments, this control signal may be to speed up or slow down the blower  32 . In an optional step S 3 , depending upon the measured pressure done at step S 1 , the controller  12  may send a control signal to other system components such as the combustion device  42  and/or the air/fuel mixture device  24 . 
         [0028]    In embodiments where the pressure measuring device  15  is a pressure switch, if there is little or no difference (the difference falls below a minimal threshold) the pressure switch  15  may send a signal to the controller  12  indicating such. The controller  12  will then detect that the airflow through the system  10  is below a minimum threshold and then shut down the blower  32  and or combustion device  42 . In some embodiments, the controller  12  may also shut down other components such as the air/fuel mixture device  24 . In some embodiments where the pressure measuring device  15  is a pressure switch  15  and the difference in pressure detected in chambers  54  and  56  falls below a minimum threshold, the controller  12  may increase the speed of the blower  32  and wait a preset amount of time to see if there is a pressure increase in chamber  54  with respect to chamber  56 . If the difference in pressure between chambers  54  and  56  still remain below the minimum threshold after the set amount of time, the controller  12  may then shut down any, all, or some of the other components in the system  10  such as, but not limited to, the blower  32 , the combustion device  42 , and the air/fuel mixture device  24 . 
         [0029]    In embodiments where the pressure measuring device  15  is a pressure sensor, then the controller  12  may have different minimum threshold differences in pressure between the chambers  54  and  56  depending upon the speed of the blower  32 . If the detected difference in pressure falls below a minimum threshold for a given speed, the controller  12  may shut down one, all, or some of the components of the system such as, but not limited to, the blower  32 , the combustion device  42 , or the air/fuel mixture device  24 . In other embodiments, when the pressure difference between the chambers  54  and  56  fall below a minimum threshold for a given blower speed, the controller  12  may increase the blower speed and await a set amount of time and re-measure the difference in pressures between the chambers  54  and  56 . If the pressure differential is still below minimum threshold, then the controller  12  may shut down any, all, or portions of the system such as, but not limited to, the blower  32 , the combustion device  42 , and/or the air/fuel mixture device  24 . 
         [0030]    In some embodiments, when the detected pressure differential between the chambers  54  and  56  falls below a minimum threshold, the controller  12  may also set off an alarm indicator in addition to shutting down various components of the system  10 . 
         [0031]    After reviewing this disclosure, one of ordinary skill in the art will understand what minimum thresholds should be for a given system  10 . The system operator will also understand what time periods are appropriate, if any, for measuring the pressure differential between chambers  54  and  56  after a first control signal has been sent. One of ordinary skill in the art, after viewing this disclosure, will also understand what size the orifice  52  should be for a specific system  10 . Other dimensions and settings will also be understood. 
         [0032]    Although an example of the system is shown and described, for home or commercial heating systems, it will be appreciated that other combustion systems can use features discussed herein. 
         [0033]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described. Accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.