Patent Publication Number: US-2020284485-A1

Title: Expansion valve

Description:
TECHNICAL FIELD 
     The present invention relates to an expansion valve for use in refrigeration cycles. 
     BACKGROUND OF THE INVENTION 
     In general vehicles, in order to provide a comfortable interior environment with less noise, noise reduction during the operation of car air conditioners, for instance, is required. There are various causes of the noise generated by the operation of car air conditioners, but the expansion valve used for refrigeration cycles is sometimes noted as a noise generation source. In this type of expansion valve, the high-pressure refrigerant emits a characteristic operation sound when the high-pressure refrigerant is decompressed by the orifice and travels to the evaporator, and particularly in cases in which the expansion valve is installed on the partition wall that separates the engine compartment from the vehicle compartment, this operation sound is easily transmitted to the inside of the vehicle, such that there is demand for noise reduction. In order to reduce such noise, various proposals have been made regarding expansion valves. 
     Patent Document 1 discloses an expansion valve in which a rectifier with a throttle opening is provided in the outlet passage leading toward the evaporator. According to such an expansion valve, when passing through the throttle opening, the air bubbles in the refrigerant are subdivided, thereby reducing the noise caused by the rupturing of these air bubbles. 
     CITATION LIST 
     Patent Literature 
     [Patent Document 1] Japanese Laid-Open Patent Application No. 2013-231571 
     SUMMARY OF INVENTION 
     Technical Problem 
     In addition to the noise caused by the rupture of air bubbles, noise caused by turbulent flow of the refrigerant may occur, but by providing the rectifier, such noise can also be reduced. More specifically, the refrigerant throttled by the orifice of the expansion valve expands until the refrigerant reaches the outlet passage, and then the traveling direction of the refrigerant changes by approximately 90 degrees, which may invite the risk of turbulent flow which causes noise. Therefore, by throttling the expanded refrigerant once again with the rectifier throttle opening, it is possible to prevent the generation of turbulence and to achieve noise reduction. This is referred to as what is known as a “muffler effect”. 
     Incidentally, in order to exhibit a sufficient muffling effect, it is desirable to enlarge the volume of the space through which the refrigerant passes from the orifice to the rectifier as much as possible. On the other hand, in car air conditioners and the like, the miniaturization of components is prioritized, and it is desirable to miniaturize the expansion valve as much as possible. However, if the expansion valve is miniaturized, the volume of the space from the orifice to the rectifier is also restricted, and there is a risk that the muffler effect cannot be sufficiently exhibited. 
     It is an object of the present disclosure to provide an expansion valve which is compact and can further enhance muffling performance. 
     Solution to Problem 
     In order to achieve the above object, the expansion valve according to the present invention includes a valve main body including an inlet passage configured to introduce a high-pressure refrigerant, a valve chamber configured to communicate with the inlet passage, an expansion chamber that includes an orifice configured to reduce a pressure of the refrigerant introduced into the valve chamber, and an outlet passage disposed downstream of the expansion chamber and configured to discharge the refrigerant that passes through the expansion chamber, a rectifier disposed in the valve main body and configured to partition the expansion chamber and the outlet passage, a valve member configured to open and close the orifice, and a valve member driving device configured to drive the valve member, wherein the rectifier includes a hollow convex portion projecting toward the outlet passage and a throttle hole formed at a distal end of the hollow convex portion. 
     Preferably, the hollow convex portion is cylindrical, and has an outer diameter less than an inner diameter of a pipe connected to the outlet passage. 
     Preferably, at least a portion of the hollow convex portion is disposed inside the pipe. 
     The rectifier is preferably formed by press forming a metallic plate. 
     Advantageous Effects of Invention 
     According to the present disclosure, it is possible to provide an expansion valve which is compact and can further enhance muffling performance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram that schematically illustrates the entire configuration of an expansion valve according to the present embodiment. 
         FIG. 2  is an enlarged view of an area AR around the orifice. 
         FIG. 3  is a perspective view of the rectifier. 
         FIG. 4  is a schematic cross-sectional view that schematically illustrates the application of the expansion valve to a refrigerant circulation system according to the present embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     Referring now to the drawings, an expansion valve  1  according to an embodiment of the present disclosure will be described. It should be noted that in the following description of the embodiments and comparative examples, parts and members having the same functions are denoted by the same reference numerals, and redundant description of parts and members denoted by the same reference numerals is omitted. 
     (Definition of Directions) 
     In this specification, the direction from the valve body  3  to the actuation rod  5  is defined as the “upward direction” and the direction from the actuation rod  5  to the valve body  3  is defined as the “downward direction” on the paper surface of the drawings. 
     (Overview of Expansion Valve) 
     An overview of the expansion valve  1  in the present embodiment will be described with reference to  FIG. 1  to  FIG. 3 .  FIG. 1  is a diagram that schematically illustrates the entire configuration of an expansion valve  1  according to the present embodiment together with a pipe connected to an evaporator. It should be noted that, in  FIG. 1 , the portion corresponding to the power element  8  is illustrated in a side view, and the remaining portions are illustrated in a cross-sectional view.  FIG. 2  is an enlarged view of an area AR around the orifice, where (a) is an enlarged view of the present embodiment, and (b) and (c) are enlarged views of the same portion in the comparative examples.  FIG. 3  is a perspective view of the rectifier. 
     The expansion valve  1  comprises an aluminum valve main body  2  with a valve chamber VS, a valve body  3 , a biasing member  4 , an actuation rod  5 , and a ring spring  6 . 
     In addition to the valve chamber VS, the valve main body  2  includes a first flow path  21  and a second flow path  22 . The first flow path  21  is, for example, a supply-side flow path (also referred to as an inlet flow path), and the valve chamber VS is supplied with fluids through the supply-side flow path. The second flow path  22  is, for example, a discharge-side flow path (also referred to as an outlet flow path), and the fluid in the valve chamber VS is discharged out of the expansion valve through the discharge-side flow path. Connected to the second flow path  22  is a pipe H 1  which extends to and is connected to an evaporator (not illustrated in  FIG. 1 ). On the outer periphery of the end of the pipe H 1 , an O-ring OR is arranged so as to abut against the inner wall of the second flow path  22 , thereby preventing leakage of the refrigerant. 
     A rectifier  30  is disposed near the entrance of the second flow path  22  of the valve main body  2  so as to enter the pipe H 1 . As illustrated in  FIG. 3 , the rectifier  30  has a substantially top hat shape, and specifically, has a circular sheet portion  31  and a hollow cylindrically shaped hollow convex portion  32  integrally provided with the circular sheet portion  31 , and an opening (also referred to as a throttle hole)  33  formed at the distal end of the hollow convex portion  32 . It should be noted that the circular sheet portion  31  and the hollow convex portion  32  are eccentric to each other, but may be coaxial. 
     In the present embodiment, the rectifier  30  is formed by press-forming a plate material such as SUS, but the rectifier  30  may be formed of a resin. Alternatively, the circular sheet portion  31  and the hollow convex portion  32  may be separate bodies, which form the rectifier when joined together. The outer periphery of the circular sheet portion  31  is attached to the inner wall of the second flow path  22  by a method such as caulking or press-fitting. 
     In  FIG. 1 , when the outer diameter of the hollow convex portion  32  is defined as D 2  and the inner diameter of the pipe H 1  is defined as D 1 , the relationship D 2  D 1  is satisfied. Accordingly, as illustrated in  FIG. 1 , the rectifier  30  can be assembled by causing the hollow convex portion  32  to enter into the interior of the pipe H 1 . However, in consideration of the assembly error with the pipe H 1 , it is more desirable to set a relationship of D 2 &lt;D 1  to ensure smooth assembly. 
     The valve body  3  is located in valve chamber VS. When the valve body  3  is seated on the valve seat  20  of the valve main body  2 , the first flow path  21  and the second flow path  22  are not in communication with each other. On the other hand, when the valve body  3  is separated from the valve seat  20 , the first flow path  21  and the second flow path  22  are in communication. 
     The biasing member  4  biases the valve body  3  towards the valve seat  20 . The biasing member  4  is, for example, a coiled spring. 
     The lower end of the actuation rod  5  contacts the valve body  3 . In addition, the actuation rod  5  can press the valve body  3  in the opening direction against the biasing force of the biasing member  4 . When the actuation rod  5  moves downwards, the valve body  3  is separated from the valve seat  20  and the expansion valve  1  is opened. 
     The space from the small diameter orifice  27  located downstream of the valve seat  20  to the opening  33  of the rectifier  30  is referred to as expansion chamber EX. That is, the rectifier  30  partitions the expansion chamber EX and the second flow path  22 . A bolt hole  25  used for fastening to another member is formed by interposing thin walls with respect to the expansion chamber EX. 
     The ring spring  6  is a vibration isolating member for suppressing the vibration of the actuation rod  5 . The ring spring  6  is disposed between the outer peripheral surface  55  of the actuation rod  5  and the inner peripheral surface  26   a  of the valve main body  2 . However, the ring spring  6  is not necessarily required. 
     A return flow path (also known as a return passage)  23  is formed in the upper portion of the valve main body  2 . Connected to the return flow path  23  is a pipe H 2  that extends from the evaporator (not illustrated in  FIG. 1 ). On the outer periphery of the end of the pipe H 2 , an O-ring OR is arranged so as to abut against the inner wall of the return flow path  23 , thereby preventing leakage of the refrigerant. 
     Next, the effect of the present embodiment will be described via comparison with a comparative example. First, in Comparative Example 1 illustrated in  FIG. 2( b ) , the rectifier  30 A is composed of only the circular sheet portion  31 , and the circular sheet portion  31  has an opening  33 . The opening  33  is made to have the same shape as the opening  33  of the rectifier  30 . In addition, the volume of the expansion chamber EX is relatively small compared to the present embodiment. 
     Also, in Comparative Example 1 as illustrated in  FIG. 2( b ) , using the so-called muffler effect, it is possible to reduce, to some extent, the passage noise emitted by the refrigerant after passing between the valve seat  20  and the valve body  3  and the orifice  27  at the time of valve opening. 
     On the other hand, as illustrated in Comparative Example 2 as illustrated in  FIG. 2( c ) , even if the same rectifier  30 A is used, the so-called muffler effect is enhanced by increasing the volume of the expansion chamber EX, and a larger passage noise reduction effect can be expected. However, when the bolt hole  25  is provided in the valve main body  2 , for example, the volume of the expansion chamber EX is limited to avoid interference, and it is difficult to obtain a further reduction in passage noise. 
     Therefore, in the present embodiment, by using a rectifier  30  having the hollow convex portion  32  as illustrated in  FIG. 2( a ) , the volume of the expansion chamber EX including the orifice can be further enlarged, and the so-called muffler effect can be further enhanced, so that a greater passage noise reduction effect can be expected. In particular, by inserting a portion of the hollow convex portion  32  into the pipe H 1 , it is possible to suppress interference with the pipe H 1 , and to maintain a compact outer shape of the valve main body  2  while increasing the volume of the expansion chamber EX. Such effects are of particular importance in the expansion valves used for car air conditioners and the like. It should be noted that the diameter and length of the hollow convex portion  32 , the area and the shape of the opening  33 , and the like can be selected to be optimal according to the specifications of the products. In addition, the diameter of the holes of the expansion chamber EX (the diameter perpendicular to the central axes of the hollow convex portion  32 ) is not limited to the size illustrated in  FIG. 2( a ) , and can be any diameter. 
     (Application Example of Expansion Valve  1 ) 
     An application example of the expansion valve  1  will be described with reference to  FIG. 4 .  FIG. 4  is a schematic cross-sectional view that schematically illustrates an example in which the expansion valve  1  in the above-described embodiment is applied to a refrigerant circulation system  100 . 
     In the embodiment illustrated in  FIG. 4 , the expansion valve  1  is fluidly connected to a compressor  101 , a condenser  102 , and an evaporator  104 . 
     In addition, the expansion valve  1  includes a power element  8  and a return flow path  23  in addition to the valve main body  2 , the valve body  3 , the biasing member  4 , the actuation rod  5 , the ring spring  6 , the first flow path  21  and the second flow path  22 . The valve body  3  and the valve seat  20  constitute a valve member, and the power element  8 , the biasing member  4  and the actuation rod  5  constitute a valve member driving device. 
     Referring to  FIG. 4 , the refrigerant pressurized by the compressor  101  is liquefied by the condenser  102 , and sent to the expansion valve  1 . In addition, the refrigerant adiabatically expanded in the expansion valve  1  is delivered to the evaporator  104  through the pipe H 1 , and heat exchanged in the evaporator  104  with the air flowing around the evaporator. The refrigerant returning from the evaporator  104  is returned from the pipe H 2  to the compressor  101  through the expansion valve  1  (more specifically, the return flow path  23 ). 
     Expansion valve  1  is supplied with high-pressure refrigerant from the condenser  102 . More specifically, the high pressure refrigerant from the condenser  102  is supplied to the valve chamber VS via the first flow path  21 . In the valve chamber VS, the valve body  3  is disposed opposite the valve seat  20 . The valve body  3  is supported by a valve body support  29 , and the valve body support  29  is biased upwardly by the biasing member  4 , (for example, a coiled spring). In other words, the valve body  3  is biased by the biasing member  4  toward the valve closing direction. The biasing member  4  is disposed between the valve body support  29  and the biasing member receiving member  24 . In the embodiment illustrated in  FIG. 4 , the biasing member receiving member  24  is a plug that is mounted on the valve main body  2  to seal the valve chamber VS. 
     When the valve body  3  is seated on the valve seat  20  (in other words, when the expansion valve  1  is in the closed state), the first flow path  21  on the upstream side of the valve chamber VS and the second flow path  22  on the downstream side of the valve chamber VS are not in communication with each other. On the other hand, when the valve body  3  is separated from the valve seat  20  (in other words, when the expansion valve  1  is in an open state), the refrigerant supplied to the valve chamber VS is delivered to the evaporator  104  through the second flow path  22 . At this time, by entering the expansion chamber EX having a large volume after passing through the orifice  27  and then passing through the opening  33  of the rectifier  30 , the passage noise is effectively reduced. The switching between the closed state and the open state of the expansion valve  1  is carried out by the actuation rod  5  connected to the power element  8 . 
     In the embodiment illustrated in  FIG. 4 , the power element  8  is disposed at the upper end of the expansion valve  1 . The power element  8  includes an upper lid member  81 , a receiving member  82  that has an opening at its center, and a diaphragm (not illustrated in the figures) disposed between the upper lid member  81  and the receiving member  82 . The first space surrounded by the upper lid member  81  and the diaphragm is filled with a working gas. 
     The lower surface of the diaphragm is connected to the actuation rod via a diaphragm support member. Therefore, when the working gas in the first space is liquefied, the actuation rod  5  moves upward, and when the liquefied working gas is vaporized, the actuation rod  5  moves downward. In this way, the switching between the open state and the closed state of the expansion valve  1  is carried out. 
     The second space between the diaphragm and the receiving member  82  is in communication with the return flow path  23 . Therefore, the phase (gas phase, liquid phase, or the like) of the working gas in the first space changes in accordance with the temperature and pressure of the refrigerant flowing through the return flow path  23 , and the actuation rod  5  is driven. In other words, in the expansion valve  1  illustrated in  FIG. 4 , the quantity of the refrigerant supplied from the expansion valve  1  to the evaporator  104  is automatically adjusted in accordance with the temperature and pressure of the refrigerant returning from the evaporator  104  to the expansion valve  1 . In the embodiment illustrated in  FIG. 4 , the return flow path  23  communicates with the concave portion  26 , and the concave portion  26  is disposed below the return flow path  23 . 
     It should be noted that the present invention is not limited to the above-mentioned embodiments. Variations of any of the components of the embodiments described above are possible within the scope of the present invention. In addition, any component can be added or omitted in the above-described embodiment. 
     For example, instead of the hollow cylindrical shape, the hollow convex portion of the rectifier  30  may have a hollow tapered shape (a hollow frusto-conical shape) or a hollow square cylindrical shape. 
     REFERENCE SIGNS LIST 
     
         
           1 : expansion valve 
           2 : valve main body 
           3 : valve body 
           4 : biasing member 
           5 : actuation rod 
           6 : ring spring 
           8 : power element 
           20 : valve seat 
           21 : first flow path 
           22 : second flow path 
           23 : return flow path 
           24 : biasing member receiving member 
           25 : bolt hole 
           26 : concave portion 
           27 : orifice 
           30 : rectifier 
           31 : circular sheet portion 
           32 : hollow convex portion 
           33 : opening 
           100 : refrigerant circulation system 
           101 : compressor 
           102 : condenser 
           104 : evaporator 
         EX: expansion chamber 
         H 1 , H 2 : pipe 
         VS: valve chamber