Patent Publication Number: US-2020300518-A1

Title: Thermal expansion valve for hvac

Description:
FIELD 
     The present disclosure relates to a thermal expansion valve (TXV) for a heating, ventilation, and air conditioning system (HVAC). 
     BACKGROUND 
     This section provides background information related to the present disclosure, which is not necessarily prior art. 
     Heating, ventilation, and air conditioning (HVAC) systems typically include a thermal expansion valve (TXV), which controls the amount of refrigerant released into an evaporator. While current TXVs are suitable for their intended use, they are subject to improvement. For example, current TXVs fail to filter out bubbles in the sub-cooled refrigerant. Such bubbles often cause TXV hiss noise, which can be annoying to occupants of a vehicle that the HVAC system is installed in. To reduce the hiss noise, butyl rubber has been used to weigh down the TXV, however, the use of butyl rubber is undesirable because it adds significant costs to the HVAC system. An improved TXV that is able to reduce the hiss noise without using butyl rubber would therefore be desirable. The present disclosure advantageously includes an improved TXV that reduces TXV hiss noise without the use of butyl rubber. The present disclosure provides numerous other advantages and unexpected results as well, as explained in detail herein and as one skilled in the art will appreciate. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     The present disclosure includes a thermal expansion valve (TXV) for a heating, ventilation, and air conditioning (HVAC) system. The TXV includes a first inlet chamber configured to receive refrigerant from a condenser of the HVAC system. The first inlet chamber includes a first portion and a second portion with an aperture therebetween that fluidly connects the first portion and the second portion together. The TXV also has a first outlet chamber through which the refrigerant from the condenser exits the TXV. Bubbles in the refrigerant rise due to buoyancy and are trapped in the first portion of the first inlet chamber with the help of the aperture. This restricts bubbles from flowing to the first outlet chamber and passing through the TXV until bubble size is smaller than aperture opening. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of select embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  illustrates an exemplary HVAC system including a TXV in accordance with the present disclosure; and 
         FIG. 2  is a cross-sectional view of the TXV of  FIG. 1 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
       FIG. 1  illustrates an exemplary heating, ventilation, and air conditioning (HVAC) system  10 . The HVAC system  10  may be any suitable HVAC system, such as any suitable vehicle HVAC system. The HVAC system  10  may be configured for use in any suitable vehicle, such as any suitable passenger vehicle, sport utility vehicle, recreational vehicle, mass transit vehicle, military vehicle/equipment, construction vehicle/equipment, watercraft, aircraft, etc. The HVAC system  10  may also be any suitable non-vehicular HVAC system, such as a building HVAC system. 
     The HVAC system  10  includes a thermal expansion valve (TXV)  12  in accordance with the present disclosure. The TXV  12  is connected to various refrigerant conduits  14 , which deliver any suitable refrigerant to and from the TXV  12  from various other components of the HVAC system  10 . The other components of the HVAC system  10  include a compressor  20 , which compresses the refrigerant into a highly pressurized gas. The highly pressurized gas is directed through a condenser  22 , where the refrigerant condenses into a highly pressurized liquid and radiates heat. From the condenser  22 , the refrigerant flows through a dryer  24 , which removes excess water from the refrigerant. From the dryer  24 , the refrigerant flows through the TXV  12 . The refrigerant enters the TXV  12  as a highly pressurized subcooled liquid, and exits the TXV  12  as a lower pressure vapor/liquid mixture. The lower pressure refrigerant flows through an evaporator  26 , where the refrigerant absorbs heat to cool the surrounding environment, such as a vehicle passenger cabin. The refrigerant exits the evaporator  26  as a super-heated vapor, and flows through the TXV  12  back to the compressor  20 . The HVAC system  10  further includes a fan  30 , which generates airflow across the condenser  22  to facilitate radiation of heat from the refrigerant flowing through the condenser  22 . A blower  32  generates airflow across the evaporator  26  to facilitate heat absorption. 
     With continued reference to  FIG. 1 , and additional reference to  FIG. 2 , the TXV  12  will now be described in additional detail. The TXV  12  includes a body  50  defining a first inlet chamber, which has a first portion  52 A and a second portion  52 B. A first inlet opening  54  of the first portion  52 A is connected to the refrigerant conduit  14  for the delivery of the sub-cooled liquid refrigerant from the condenser  22  into the first inlet chamber. A partition  56  divides the first inlet chamber into the first portion  52 A and the second portion  52 B. The partition  56  defines an aperture  58  between the partition  56  and the body  50 . In the example illustrated, the partition  56  extends generally parallel to a longitudinal axis A of the TXV  12 . The aperture  58  is sized to prevent bubbles  190  present in the refrigerant from flowing freely through the aperture  58  when the bubbles  190  are larger than the aperture  58 . 
     The TXV  12  further includes a first outlet chamber  70  having a first outlet opening  72 . The first outlet opening  72  is connected to a refrigerant conduit  14  for transporting refrigerant from the TXV  12  to the evaporator  26 . The body  50  further defines an orifice  74  between the second portion  52 B of the first inlet chamber and the first outlet chamber  70  to allow refrigerant to flow from the second portion  52 B of the first inlet chamber to the first outlet chamber  70 . 
     Seated within the second portion  52 B of the first inlet chamber is a spring  80 . The spring  80  sits on an adjusting nut  82 . Between the adjusting nut  82  and the body  50  is an  0 -ring  84 . Seated on the spring  80  is a carrier  86 . A stopper or ball  88  is supported by the carrier  86  in the orifice  74  to close the orifice  74  and prevent refrigerant from flowing from the second portion  52 B of the first inlet chamber into the first outlet chamber  70 . The stopper  88  is seated at an end of a push rod  90 . Extending about the push rod  90  is an  0 -ring  92 . The push rod  90  abuts a stem  94 , which extends to a power assembly  150 . The power assembly  150  actuates the stem  94  and the push rod  90  to move the stopper  88  out from within the orifice  74  to open the orifice  74  and allow refrigerant to flow through the orifice  74  from the second portion  52 B of the first inlet chamber into the first outlet chamber  70 . The power assembly  150  will be described further herein. 
     The body  50  of the TXV  12  further defines a second inlet chamber  110  and a second outlet chamber  112 . The second inlet chamber  110  has a second inlet opening  114 , and the second outlet chamber  112  has a second outlet opening  116 . The refrigerant conduit  14  is connected to the second inlet opening to deliver super-heated vapor refrigerant from the evaporator  26  into the second inlet chamber  110 . The super-heated vapor refrigerant flows through the second inlet chamber  110  and into the second outlet chamber  112 , which is connected to, and in fluid communication with, the second inlet chamber  110 . The super-heated vapor refrigerant flows from the second outlet chamber  112  out through the second outlet  116 , and through the refrigerant conduit  14  to the compressor  20 . 
     The power assembly  150  includes a cup  152 , which is seated on a gasket  154 . Seated on the cup  152  is a lid  156 . Extending through the lid  156  is a plug  158 . The plug  158  is arranged at a center of the lid  156  along the longitudinal axis A. The power assembly  150  further includes a diaphragm  160 , which is movable to actuate the stem  94  and the push rod  90  to move the stopper  88  out from within the orifice  74  to open the orifice  74 . 
     The power assembly  150  is filled with refrigerant gas, often referred to in the art as “operation gas.” This operation gas is heated by the refrigerant flowing through the second inlet chamber  110  and the second outlet chamber  112  from the evaporator  26 . The position of the stopper (or ball)  88  is determined by the pressure difference between, above, and below the diaphragm  160 , the spring force of the spring  80 , and the pressure difference before and after the spring  80 . 
     The spring  80  is located between the adjusting nut  82  and the carrier  86 . The spring  80  is used to provide tension necessary to seat the stopper  88  under no load conditions. Adjusting the nut  82  changes the tension of the spring  80 , and is used to set the super-heat valve setting. The amount of refrigerant metering through the TXV  12  is based on a balance between the force of the spring  80  and the pressure of the operation gas within the power assembly  150 . 
     When refrigerant flows through the second inlet chamber  110  and the second outlet chamber  112 , a pressure difference occurs and the diaphragm  160  is displaced based on that difference. The diaphragm  160  is connected to the stem  94  and the push rod  90 , which pushes against the spring  80 , and moves the stopper  88  out from within the orifice  74 . Thus, as the diaphragm  160  is displaced, the orifice  74  opens to various degrees based on the displacement of the diaphragm  160 . The degree to which the orifice  74  is opened determines the volume of refrigerant that flows through the TXV  12  to the evaporator  26 . 
     The TXV  12  further includes a conduction cavity  180 . The conduction cavity  180  is in fluid communication with the first outlet chamber  70 . The conduction cavity  180  and the first outlet chamber  70  are on opposite sides of the push rod  90  and the stopper  88 . Together, the conduction cavity  180  and the first outlet chamber  70  provide a single cavity that extends across the push rod  90 . 
     Between the conduction cavity  180  and the first portion  52 A of the first inlet chamber is a conduction wall  182 . The conduction wall  182  is a portion of the body  50  between the conduction cavity  180  and the first portion  52 A. The relatively low-pressure refrigerant present in the conduction cavity  180  is cooler than the relatively high-pressure refrigerant present in the first portion  52 A of the first inlet chamber. Through the process of conduction, the cooler refrigerant in the conduction cavity  180  cools the refrigerant at the first portion  52 A, and cools the bubbles  190  present in the first portion  52 A. Cooling the bubbles  190  present in the first portion  52 A advantageously reduces the size of the bubbles  190  prior to the bubbles  190  reaching the evaporator  26 . Reducing the size of the bubbles  190  advantageously reduces the TXV hiss noise. Thus the present disclosure advantageously reduces the TXV hiss noise without the need for using relatively expensive butyl rubber to weight down the TXV valve, as is done with various existing TXVs. One skilled in the art will appreciate that the present disclosure provides numerous additional advantages as well and various unexpected results. 
     The TXV  12  converts subcooled liquid refrigerant into low-temperature/low-pressure, two-phase vapor/liquid mixture by throttling the refrigerant flow. The vapor/liquid mixture then travels through the evaporator  26 , where the low-temperature/low-pressure refrigerant absorbs heat from a passenger cabin, for example, as the remaining liquid refrigerant evaporates inside the evaporator  26  to provide cooling. The low-pressure, super-heated vapor refrigerant travels to the compressor  20  and is compressed to a high-pressure/high-temperature super-heated vapor. The high-temperature/high-pressure vapor from the compressor  20  is condensed into a liquid in the condenser  22  using outside air. The refrigerant is then directed back to the TXV  12  and enters the TXV  12  as a subcooled liquid where the loop begins again. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated  90  degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.