Check valve and refrigeration cycle system

Abstract

To provide a check valve and a refrigeration cycle system which improve sealing performance, suppress decrease in a Cv value, and prevent increase in the size.SOLUTION: A check valve 1 includes a cylindrical outer pipe extending in an axial direction, a valve seat body 13 disposed so as to arrange an integral or separate valve seat 1311 inside the outer pipe, and a valve element 15. The valve seat body 13 includes a valve port 1311b, a cylinder 132 which extends to one side X1 in an axial direction continuously from the valve port 1311b and can constitute a part of the outer pipe, and an inlet opening 132a which is continuous with the cylinder 132 and is opened to the one side X1. An inside diameter R2 of the valve port 1311b is smaller than an inside diameter R1 of the inlet opening 132a, and an inner peripheral surface 132b of the cylinder 132 is formed with a taper of a prescribed inclination angle θ from the inlet opening 132a to the valve port 1311b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a check valve and a refrigeration cycle system. [Background technology]

[0002] A known check valve includes an outer pipe having an internal valve chamber, a valve seat member provided inside the outer pipe and having a valve port, and a valve disc provided movably within the valve chamber for opening and closing the valve port, allowing fluid from a primary pipe connected to the outer pipe to flow through the valve port to a secondary pipe, and preventing backflow of fluid from the secondary pipe by closing the valve port with the valve disc (see, for example, Patent Documents 1 and 2). The check valve described in Patent Document 1 has a valve seat member fixed to the end of the primary pipe (inlet joint), an outer pipe fixed around the outer periphery of the valve seat member, the inner diameter of the primary pipe and the inner diameter of the valve port of the valve seat member are the same, the valve seat and the valve disc have flat abutment surfaces, and the valve port is closed when the abutment surfaces abut against each other. The check valve described in Patent Document 2 has an inner diameter of the valve opening of the valve seat member that is smaller than the inner diameter of the primary pipe (small diameter section, inlet port), a tapered surface is formed in the valve section of the valve body, and the valve opening is formed in an edge-like shape without a tapered surface, so that the valve opening is closed when the tapered surface abuts against the edge-like section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-19265 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-44418 Summary of the Invention [Problem to be solved by the invention]

[0004] In a structure in which the valve seat and disc abut at an edge and a tapered surface, such as the check valve described in Patent Document 2 (this structure is defined as a tapered / edge seal structure), if the disc is seated at an angle, a gap forms on one side, making the valve prone to leakage, making it difficult to improve sealing performance. Furthermore, if the inner diameter of the valve port is smaller than the inner diameter of the primary pipe, as in the check valve described in Patent Document 2, a step is formed between the inner surface of the primary pipe and the valve seat member, increasing pressure loss, lowering the Cv value (a capacity coefficient), and reducing the fluid flow rate. In contrast, a structure in which flat abutment surfaces abut each other, such as the check valve described in Patent Document 1 (this structure is defined as a flat seal structure), can be expected to provide high sealing performance. Furthermore, if the inner diameter of the primary pipe and the inner diameter of the valve port of the valve seat member are the same, as in the check valve described in Patent Document 1, there is no step between the inner surface of the primary pipe and the valve seat member, resulting in no pressure loss and a high Cv value. However, in this structure, the valve seat member has a large diameter in order to make the inner diameter of the valve port the same as the inner diameter of the primary pipe, and the outer periphery of this member is surrounded by an outer pipe, which causes the problem of the check valve becoming large.

[0005] An object of the present invention is to provide a check valve and a refrigeration cycle system that improve sealing performance, suppress a decrease in Cv value, and prevent an increase in size. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, the check valve of the present invention comprises an outer pipe portion extending in an axial direction, a valve seat body provided so as to dispose a valve seat portion inside the outer pipe portion, and a valve seat body that can abut against the valve seat portion at flat abutment surfaces. cylindrical a valve body; , which is installed in the middle of the fluid flow path in a closed circuit systema check valve, the valve seat body having a valve orifice that opens to the valve seat portion, a hollow cylindrical portion that is continuous with the valve orifice and extends to one side in the axial direction, and an inlet opening that is continuous with the cylindrical portion and opens to the one side, the inner diameter of the valve orifice being smaller than the inner diameter of the inlet opening, the inner circumferential surface of the cylindrical portion being tapered at a predetermined inclination angle from the inlet opening to the valve orifice and continuing without steps with the inner circumferential surface of the valve orifice, the inclination angle being 10° to 45°, and the length of the cylindrical portion in the axial direction being greater than 1 / 2 of the inner diameter of the valve orifice. The valve body is provided slidably in the axial direction relative to the valve seat body, and a plurality of grooves extending in the axial direction are provided on the outer circumferential surface of the valve body. It is characterized by:

[0007] According to the present invention, the valve disc and the valve seat abut against each other through flat abutment surfaces. This makes the valve disc less likely to tilt when seated, compared to conventional structures with the above-described tapered / edge seal structure, improving the sealing performance of the check valve. Furthermore, the inlet opening and the valve port are connected by the tapered inner circumferential surface of the cylindrical portion, eliminating a step between the inlet opening and the valve port. This allows for smoother fluid flow between the inlet opening and the valve port. This improves the Cv value compared to conventional structures in which a step is formed between the inner surface of the primary pipe and the valve seat member. Furthermore, because the inner diameter of the valve port is smaller than the inner diameter of the inlet opening on the inner periphery of the cylindrical portion, this difference can be utilized to provide a flat valve seat around the valve port, preventing the outer diameter of the valve seat body from becoming larger. This results in a check valve that improves sealing performance, suppresses a decrease in the Cv value, and prevents enlargement of the valve seat body.

[0008] In this case, it is preferable that the outer pipe portion includes a primary pipe communicating with the inlet opening, and the inner diameter of the inlet opening is set to be the same as the inner diameter of the primary pipe. With this configuration, no step is formed between the primary pipe and the inlet opening, which makes it possible to smooth the flow of fluid between the primary pipe and the inlet opening and improve the Cv value.

[0009] It is also preferable that the outer tube portion includes a primary tube communicating with the inlet opening, and the axial length of the cylindrical portion is greater than the axial length of the valve port.

[0013] Furthermore, a gap may be provided between the inlet opening and the edge of the primary pipe. With this configuration, even when a gap is formed between the inlet opening and the edge of the primary pipe, it is possible to obtain a check valve that improves sealing performance, suppresses a decrease in Cv value, and prevents an increase in size.

[0014] The inlet opening may have a straight portion extending a predetermined length in the axial direction.

[0015] The present invention also provides a refrigeration cycle system including any one of the check valves described above. With this configuration, the refrigeration cycle system can be configured using a check valve that improves sealing performance, suppresses a decrease in the Cv value, and prevents the check valve from becoming larger. [Effects of the Invention]

[0016] According to the present invention, a check valve and a refrigeration cycle system can be obtained that improve sealing performance, suppress a decrease in Cv value, and prevent an increase in size. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an overall cross-sectional view of a check valve according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the valve seat body in FIG. 1. [Figure 3] FIG. 4 is a diagram showing a Cv value simulation graph of the check valve according to the first embodiment. [Figure 4] FIG. 4 is an overall cross-sectional view of a check valve according to a modified example of the first embodiment. [Figure 5] FIG. 6 is an overall cross-sectional view of a check valve according to a second embodiment. [Figure 6] FIG. 10 is an overall cross-sectional view of a check valve according to a third embodiment. [Figure 7] FIG. 11 is an overall cross-sectional view of a check valve according to a modified example of the third embodiment. [Figure 8] A refrigeration cycle system equipped with a check valve shown in any one of Figures 1 to 7. DETAILED DESCRIPTION OF THE INVENTION

[0018] A check valve 1 according to a first embodiment of the present invention will be described below with reference to Figures 1 to 3. The check valve 1 according to this embodiment is a valve device that is installed in the middle of a refrigerant flow path in a refrigeration cycle system, and includes an outer pipe body 11, a valve body 12, and a valve element 15. The valve body 12 is made up of a valve seat body 13 and a valve holder 14.

[0019] In the following description, the direction along the axis X of the outer pipe body 11 is referred to as the axial direction, one side in the axial direction is referred to as one side X1, and the other side in the axial direction is referred to as the other side X2. The direction from one side X1 to the other side X2 is referred to as the forward flow direction of the refrigerant, and the direction opposite to the forward flow direction is referred to as the reverse flow direction. This is for the sake of convenience of description only, and does not necessarily coincide with the directions in the actual usage state of the check valve 1, and does not limit the directions in the actual usage state of the check valve 1.

[0020] The outer pipe body 11 is a cylindrical member extending in the axial direction, and is formed by cutting or the like using a metal material such as stainless steel. The other side X2 portion of the valve body 12 is housed inside the outer pipe body 11. An end of one side X1 of a copper outlet pipe 16 (secondary pipe) connected to a pipe (not shown) is inserted into the open end of the other side X2 of the outer pipe body 11 toward the one side X1, and in that state they are connected by brazing or the like.

[0021] As described above, the valve body 12 includes the valve seat body 13 and the valve holder 14. The valve seat body 13 is a substantially cylindrical part provided on one side X1 of the outer pipe body 11, and is formed by cutting or the like using a metal material such as stainless steel.

[0022] The valve seat body 13 includes a reduced diameter portion 131, a cylindrical portion 132, and a connecting portion 133. The reduced diameter portion 131 is a portion connected to the end of one side X1 of the outer pipe body 11, and its outer diameter is smaller than that of the remaining portions of the valve seat body 13. The outer peripheral surface of the reduced diameter portion 131 fits into the inner peripheral surface of the outer pipe body 11, and in this state (i.e., when placed inside the outer pipe body 11), the valve seat body 13 is fixed to the outer pipe body 11 by laser welding or the like. A stepped valve seat portion 1311 recessed toward the one side X1 is formed on the inner surface of the reduced diameter portion 131. That is, a portion of the valve seat portion 1311 is placed inside the outer pipe body 11. The surface of the valve seat portion 1311 facing the other side X2 forms a flat abutment surface 1311a (seat surface) on which the valve disc 15 is seated. A valve port 1311b that opens in the axial direction is formed in the center of the valve seat portion 1311. The radial position of the abutment surface 1311a is set on the axis X side (the radial central axis side) so as to utilize the difference between an inner diameter R1 of an inlet opening 132a (described later) and an inner diameter R2 of the valve port 1311b, which makes it difficult for the valve seat body 13 to be made larger in the radial direction than an inlet pipe 17 (described later).

[0023] The cylindrical portion 132 is a cylindrical portion that continues from the valve opening 1311b and extends toward the one side X1, and an inlet opening 132a that opens toward the one side X1 is formed at the end of the one side X1. That is, the inlet opening 132a continues from the cylindrical portion 132 and opens toward the one side X1. As shown in FIG. 2, the inner diameter R1 of the inlet opening 132a is larger than the inner diameter R2 of the valve opening 1311b and is set to be the same as the inner diameter R3 of the inlet pipe 17 (primary pipe) described below. Therefore, the inner diameter of the cylindrical portion 132 decreases from the inlet opening 132a toward the valve opening 1311b, and the inner circumferential surface 132b of the cylindrical portion 132 is formed to have a taper with a predetermined inclination angle θ from the inlet opening 132a to the valve opening 1311b.

[0024] The predetermined inclination angle θ of the taper of the inner circumferential surface 132b refers to the angle of the angle formed by the upper inner circumferential surface 132b and the lower inner circumferential surface 132b when the upper inner circumferential surface 132b and the lower inner circumferential surface 132b are virtually extended until they come into contact with each other in the cross-sectional view shown in Figure 2.

[0025] If the tubular portion 132 is not provided, the inner circumferential surface 132b will not be tapered. Therefore, a step will be created between the inlet opening 132a and the valve opening 1311b due to the difference between the inner diameter R1 of the inlet opening 132a and the inner diameter R2 of the valve opening 1311b, and the inclination angle θ will be substantially 180°. In this case, the fluid flowing from the inlet pipe 17 will be partially blocked by the step, making it difficult to allow a large amount of fluid to flow. Therefore, the predetermined inclination angle θ of the tapered inner circumferential surface 132b of the tubular portion 132 is preferably set to 45° or less to achieve the effects described below. In the first embodiment, the inclination angle θ shown in FIGS. 1 and 2 is 20°.

[0026] Furthermore, when the inclination angle θ is set to 45° or less, if the axial length L1 of the inner circumferential surface 132b (the axial length of the tubular portion 132) is short, the difference in size between the inner diameter R1 of the inlet opening 132a and the inner diameter R2 of the valve opening 1311b becomes small. This results in a decrease in the width of the contact surface 1311a. For this reason, it is preferable to set the axial length L1 of the inner circumferential surface 132b longer than the axial length L2 of the valve opening 1311b. Specifically, it is more preferable to set the length L1 to be longer than ½ of the inner diameter R2 of the valve opening 1311b.

[0027] As described above, in order to make the inner diameter R1 of the inlet opening 132a larger than the inner diameter R2 of the valve port 1311b, the smaller the inclination angle θ, the greater the axial length of the inner circumferential surface 132b must be secured. However, this increases the material costs and processing costs of the tubular portion 132, so it is more preferable to set the inclination angle θ to 10° or more.

[0028] The connecting portion 133 is a cylindrical portion that is continuous with the cylindrical portion 132, extends toward the one side X1, and connects to the inlet pipe 17. The inner diameter of the inner circumferential surface 133a of the connecting portion 133 is set larger than the inner diameter R1 of the inlet opening 132a. As a result, a step portion 133b that is recessed toward the other side X2 is formed between the inner circumferential surface 132b of the cylindrical portion 132 and the inner circumferential surface 133a of the connecting portion 133. The end portion of the other side X2 of the inlet pipe 17, which is connected to a piping (not shown), is inserted into the connecting portion 133 toward the other side X2 until it abuts against the step portion 133b, and is fixed in that state by brazing or the like.

[0029] The inlet pipe 17 is made of copper like the outlet pipe 16, and its inner diameter R3 is the same as the inner diameter R1 of the inlet opening 132a, as described above. This means that the inner circumferential surface of the inlet pipe 17 and the inner circumferential surface 132b of the cylindrical portion 132 are continuous without any steps, and the inlet pipe 17 communicates with the inlet opening 132a.

[0030] The valve holder 14 is a portion of the outer pipe body 11 that accommodates the valve element 15. As shown in FIG. 1, the valve holder 14 is formed in a cylindrical shape that rises from the end face of the other side X2 of the reduced diameter portion 131 toward the other side X2. The outer diameter of the valve holder 14 is set smaller than the inner diameter of the outer pipe body 11. The valve holder 14 has four communication holes 14a that penetrate the cylindrical circumferential surface in the radial direction, thereby communicating the interior of the valve holder 14 with the interior of the outer pipe body 11. A substantially annular valve stopper 18 made of a metal material such as stainless steel is attached to the inner end of the other side X2 of the valve holder 14. The valve stopper 18 is a retaining ring that prevents the valve element 15, when it abuts against it, from moving toward the other side X2 and determines the extreme position of the valve element 15's movement toward the other side X2.

[0031] The valve element 15 is a resin member that is provided so as to be axially slidable within the valve holder 14 of the valve body 12. The valve element 15 has four grooves 151a that extend in the axial direction in a substantially cylindrical valve element body 151, and is formed so that the cross section intersecting the axial direction has a substantially cross shape. The formation of the grooves 151a reduces the movement resistance of the valve element 15 relative to the valve holder 14 around the axis X, allowing the valve element 15 to slide smoothly.

[0032] A lightening portion 151b is formed in the center of the valve body 151 of the valve body 15, which is lightened so as not to penetrate from the center of the end face on the other side X2 toward the one side X1. This lightening portion 151b suppresses the occurrence of sink marks, air bubbles, etc. during resin molding of the valve body 15 and contributes to reducing the weight of the valve body 15. An end on the one side X1 of the valve body 151 forms a bottom plate portion 151c of the valve body 151, and an outer peripheral end of the bottom plate portion 151c forms an abutment surface 151c-1 that abuts against the abutment surface 1311a of the valve seat portion 1311. This allows the valve body 15 and the valve seat portion 1311 to abut against each other via the flat abutment surfaces 1311a and 151c-1.

[0033] The check valve 1 configured as described above can be used in various positions. For example, when the axial direction shown in FIG. 1 is vertical, that is, when used in a vertically installed state, it operates as follows. First, when the valve element 15 is seated on the valve seat 1311 and in the position shown in FIG. 1 (hereinafter also referred to as the valve closed position), fluid flows in the forward flow direction from the inlet pipe 17 to the outlet pipe 16. Then, the valve element 15 is pushed by the fluid flowing out from the valve port 1311b and moves to a position where it abuts against the valve stopper 18 (hereinafter also referred to as the valve open position). Then, when the flow of fluid in the forward flow direction stops, the valve element 15 falls under its own weight and seats on the valve seat 1311 again.

[0034] Furthermore, when the check valve 1 is used in a horizontal position or in an upside-down vertical position, it operates as follows. First, when the valve element 15 is in the valve-closed position, the pressure on the outlet pipe 16 side is set higher than that on the inlet pipe 17 side, and the valve element 15 is pressed against the valve seat 1311 by the pressure difference at this time, maintaining the seated position. In this state, when fluid flows in the forward direction from the inlet pipe 17 side to the outlet pipe 16 side, the valve element 15 is pressed by the fluid flowing out of the valve port 1311b and moves to the valve-open position. Then, when the forward flow of fluid stops and the pressure on the outlet pipe 16 side becomes higher than that on the inlet pipe 17 side, the pressure difference causes the valve element 15 to reseat on the valve seat 1311.

[0035] As shown in Fig. 8, this check valve 1 is installed in the middle of the refrigerant flow path in a refrigeration cycle system 50. The refrigeration cycle system 50 is used in, for example, an air conditioner such as a commercial air conditioner. This refrigeration cycle system 50 comprises an indoor heat exchanger 51, an outdoor heat exchanger 52, an expansion valve 53, a four-way valve 54, and three compressors 55 connected in parallel, all connected by piping. In order to prevent backflow of refrigerant to each compressor 55, the check valve 1 is connected between the discharge (high-pressure output) side of each compressor 55 and the four-way valve 54, with the compressor 55 on the inlet pipe 17 side and the four-way valve 54 on the outlet pipe 16 side.

[0036] During cooling operation, as shown by solid arrow D51, the refrigerant is compressed by compressor 55 and then flows through check valve 1 and four-way valve 54 to outdoor heat exchanger 52. After releasing heat in outdoor heat exchanger 52, the refrigerant flows through expansion valve 53 to indoor heat exchanger 51. After absorbing heat in indoor heat exchanger 51, the refrigerant returns to compressor 55 via four-way valve 54. During heating operation, as shown by dotted arrow D52, the refrigerant is compressed by compressor 55 and then flows through check valve 1 and four-way valve 54 to indoor heat exchanger 51. After releasing heat in indoor heat exchanger 51, the refrigerant flows through expansion valve 53 to outdoor heat exchanger 52. After absorbing heat in outdoor heat exchanger 52, the refrigerant returns to compressor 55 via four-way valve 54. The refrigeration cycle system 50 repeats these cycles to cool or heat the room.

[0037] Here, for example, under conditions of high cooling load, three compressors 55 are operated simultaneously, and each of the three check valves 1 is fully open. On the other hand, under conditions of low cooling load, operation of only one compressor 55 is sufficient, and the other two compressors 55 are not operated. In this case, the pressure on the outlet pipe 16 side of the two check valves 1 becomes higher than the pressure on the inlet pipe 17 side, causing backflow from the outlet pipe 16 side, and the two check valves 1 are closed.

[0038] Next, the relationship between the predetermined inclination angle θ (taper angle) of the inner circumferential surface 132b between the inlet opening 132a and the valve port 1311b in this embodiment and the Cv value, which is one of the capacity coefficients, will be described with reference to Figure 3. The Cv value is one of the basic coefficients used to express the capacity of a regulating valve under specified conditions, and the larger the value, the more fluid the check valve 1 can pass.

[0039] In this embodiment, the total length L3 of the check valve 1 shown in FIG. 1 was set to 120 mm, the inner diameter R3 of the inlet pipe 17 was set to 12 mm, the inner diameter R2 of the valve port 1311b was set to 10 mm, and the axial length L2 of the valve port 1311b was set to 2 mm. The inclination angle θ was then varied between 180° and 10°, and the Cv value was calculated using fluid analysis software. Note that the numerical values ​​of the calculation conditions are merely examples, and similar effects can be achieved by changing the numerical values ​​in a similar manner depending on the size of the check valve. To avoid creating a step between the inner diameter of the inlet pipe 17 and the valve port 1311b, the axial length L1 of the inner circumferential surface 132b is changed as the inclination angle θ is changed. As an exception, when the inclination angle θ is 180°, the inner circumferential surface 132b is not provided, resulting in a step between the inlet opening 132a and the valve port 1311b.

[0040] In Fig. 3, the horizontal axis represents the valve seat inlet taper angle, i.e., the inclination angle θ in this embodiment, and the vertical axis represents the percentage of the Cv value, assuming that the Cv value when the inclination angle θ is 180° is 100%. This analysis showed that the Cv value improved linearly when the inclination angle θ was in the range of 150° to 45°. Specifically, when the Cv value when the inclination angle θ was 180° was used as the reference, the Cv value improved by a maximum of 15.6 points when the inclination angle θ was 45° or less.

[0041] In a conventional check valve structure, when the inclination angle θ is 180°, i.e., when a step occurs between the inlet opening 132a and the valve port 1311b, it is conceivable to improve the Cv value by chamfering the corners of this step so that the inclination angle θ is, for example, about 90°. However, even when the Cv value when the inclination angle θ is 90° is used as the standard, the Cv value improved by up to 6.3 points when the inclination angle θ was 45° or less.

[0042] On the other hand, in the range of 45° to 10°, the Cv value increased slightly. Here, as described above, the smaller the inclination angle θ, the longer the axial length L1 of the inner circumferential surface 132b must be. However, since the material cost and processing cost of the tubular portion 132 increase as the axial length L1 of the inner circumferential surface 132b increases, it is advantageous in terms of processing costs to shorten the axial length L1 of the inner circumferential surface 132b. For this reason, it is desirable to set the inclination angle θ in the range of 10° to 45°, not below 10°.

[0043] According to the present invention, the valve disc 15 and the valve seat portion 1311 abut against each other via the flat abutment surface 151c-1 and the flat abutment surface 1311a. This makes it difficult for the valve disc 15 to tilt, improving the sealing performance of the check valve 1 compared to the conventional structure with the tapered / edge seal structure described above. Furthermore, the inlet opening 132a and the valve port 1311b are connected by the tapered inner circumferential surface 132b of the tubular portion 132, eliminating any step between the inlet opening 132a and the valve port 1311b. This allows for smoother fluid flow between the inlet opening 132a and the valve port 1311b. This improves the Cv value compared to the conventional structure in which a step is formed between the inner surface of the primary pipe and the valve seat body 13. Furthermore, since the inner diameter R2 of the valve port 1311b is smaller than the inner diameter R1 of the inlet opening 132a on the inner periphery of the cylindrical portion 132, this difference can be used to provide a flat abutment surface 1311a around the valve port 1311b, thereby preventing the outer diameter of the valve seat body 13 from becoming larger. Therefore, a check valve can be obtained that improves sealing performance, prevents a decrease in the Cv value, and prevents an increase in size.

[0044] Furthermore, according to this embodiment, the inner diameter R3 of the inlet pipe 17 (primary pipe) and the inner diameter R1 of the inlet opening 132a are set to be the same diameter, so that no step is created between the inlet pipe 17 and the inlet opening 132a, thereby smoothing the flow of fluid between the inlet pipe 17 and the inlet opening 132a and improving the Cv value.

[0045] Furthermore, by setting the inclination angle θ of the inner peripheral surface 132b of the tubular portion 132 to 45° or less, the Cv value can be improved by up to 15.6 points when the Cv value is 100% when the inclination angle θ is 180°, and by up to 6.3 points when the Cv value is 100% when the inclination angle θ is 90°.

[0046] Furthermore, according to this embodiment, the refrigeration cycle system 50 can be configured using the check valve 1 that improves sealing performance, suppresses a decrease in the Cv value, and prevents an increase in size.

[0047] The first embodiment described above merely shows a typical form of the present invention, and the present invention is not limited thereto. That is, various modifications can be made without departing from the gist of the present invention. As long as such modifications still include the configuration of the check valve and refrigeration cycle system of the present invention, they are of course included in the scope of the present invention.

[0048] For example, in the first embodiment described above, the check valve 1 is used in an air conditioner such as a commercial air conditioner. However, the check valve 1 may be used not only in commercial air conditioners but also in residential air conditioners, and is applicable not only to air conditioners but also to various freezers, refrigerators, and the like. Furthermore, in the various refrigeration cycle systems described above, as shown in FIG. 8, the check valve is not limited to being attached to the discharge side of the compressor, but can be applied to prevent backflow in various locations in the various refrigeration cycle systems. Furthermore, there are a wide variety of refrigerants available for each refrigeration cycle system (for example, various fluorocarbon-based refrigerants, hydrocarbon-based refrigerants, and natural refrigerants such as CO2 and ammonia). The check valve of the present invention can be applied to a refrigeration cycle system compatible with any of these refrigerants.

[0049] Next, a modified example of the first embodiment of the present invention will be described. FIG. 4 is an overall cross-sectional view of a check valve 1′ according to a modified example of the first embodiment. In the check valve 1′, the shape of the outlet pipe 16′, which corresponds to the above-mentioned outlet pipe 16, is different from that of the first embodiment. The outlet pipe 16′ includes a connecting pipe portion 161 connected to the other side X2 of the outer pipe main body 11, a reduced-diameter pipe portion 162 continuing from the connecting pipe portion 161 and extending toward the other side X2 with a reduced diameter, and an expanded-diameter portion 163 continuing from the reduced-diameter pipe portion 162 and extending toward the other side X2 with an expanded diameter. In other words, the outlet pipe 16′ has been subjected to both pipe-reducing and pipe-expanding processes. Even with this configuration, the same functions and effects as those of the first embodiment can be obtained.

[0050] Next, a check valve 2 according to a second embodiment of the present invention will be described. FIG. 5 is an overall cross-sectional view of the check valve 2 according to the second embodiment. The check valve 2 includes a valve seat main body 23 corresponding to the above-described valve seat main body 13. The valve seat main body 23 has a second step portion 231 recessed toward the other side X2 between a step portion 133b against which the end of the other side X2 of the inlet pipe 17 abuts and the inlet opening 132a. This forms an axial gap 232 between the edge of the other side X2 of the inlet pipe 17 connected to the valve seat main body 23 and the inlet opening 132a. This gap 232 functions as a brazing filler pool when the inlet pipe 17 is brazed to the valve seat main body 23.

[0051] The way in which the brazing filler accumulates in the gap 232 as a brazing fill portion is not constant, and sometimes the gap 232 is completely filled, but sometimes it is hardly filled at all. Also, the way in which the brazing fills varies depending on the size of the gap 232.

[0052] Generally, providing gaps 232 that may not be filled with brazing filler metal may cause fluid to remain in the gaps 232, increasing pressure loss and making it difficult for the fluid to flow. However, in the second embodiment, when the inclination angle θ of the inner circumferential surface 132b of the tubular portion 132 was set to 20° and the Cv value was calculated for a gap with no brazing filler metal, the result was 113.7%, compared to the Cv value of 100% for the inclination angle θ of 180° in the first embodiment (i.e., a structure without gaps 232). This Cv value was improved by up to 13.7 points. While this Cv value is slightly smaller than the Cv value of 115.6% for the inclination angle θ of 20° shown in FIG. 3 (i.e., when the inclination angle θ in the structure of the first embodiment is 20°), it is still significantly larger than when the inclination angle θ is 180°. Therefore, an improvement in the Cv value was observed in the second embodiment as well.

[0053] The reason why an improvement in the Cv value is observed even when gap 232 is formed is that the inner diameter of inlet pipe 17 and the inner diameter of inlet opening 132a are the same, so there is no step or the like that acts as a barrier to the straight flow of the fluid even when gap 232 is present. Therefore, the fluid flows straight from inlet pipe 17 along the inner circumference of inlet pipe 17 in the other side X2 direction, and flows smoothly along the inner circumferential surface of inlet opening 132a.

[0054] According to the present invention, even when a gap 232 occurs between the inlet opening 132a and the edge of the inlet pipe 17, a check valve 2 can be obtained that improves sealing performance, suppresses a decrease in the Cv value, and prevents the valve from becoming larger.

[0055] Here, in the first and second embodiments, the inlet pipe 17, the connection portion 133 of the valve seat body 13 of the valve body 12 (valve seat body 23 in the second embodiment), the tubular portion 132, the outer pipe body 11, and the outlet pipe 16 are parts located on the outside that constitute the check valves 1, 1', 2, and this entirety is collectively referred to as the "outer pipe portion" in the present invention. Note that in the above-mentioned first and second embodiments, the outer pipe body 11 and the valve seat body 13 are not fixed by laser welding or the like, and these two members may have an integrated structure formed from a single member, or the check valve may be constituted by sandwiching a member such as a connecting member between the outer pipe body 11 and the outlet pipe 16, and this connecting member may also be included in the outer pipe portion.

[0056] In the first and second embodiments, the other side X2 portion of the valve seat body 13 and the one side X1 end portion of the outer pipe body 11 are fixed by laser welding or the like, and therefore it cannot be said that the entire valve seat portion 1311 is located inside the outer pipe body 11, and therefore the above explanation states that only a portion is located. However, since the cylindrical portion 132 can also be said to be an outer pipe portion as described above (i.e., the cylindrical portion 132 can constitute a portion of the outer pipe portion), it can be said that the valve seat portion 1311, which is integral with the outer pipe portion, is located inside the portion of the outer pipe body 11 and the cylindrical portion 132 that constitute the outer pipe portion.

[0057] However, the configuration is not limited to this, and as shown in a third embodiment described later, the valve seat portion 1311 and the outer pipe main body 11 serving as the outer pipe portion may be configured as separate bodies (separate members). That is, the valve seat main body 13 may be provided so that the valve seat portion 1311, which is either integral with or separate from the outer pipe portion, is disposed inside the outer pipe portion.

[0058] Next, a check valve 3 according to a third embodiment of the present invention will be described. FIG. 6 is an overall cross-sectional view of the check valve 3 according to the third embodiment. The check valve 3 includes an outer pipe main body 31. The outer pipe main body 31 of the third embodiment is the "outer pipe portion" of the third embodiment, and is configured as an integrally molded copper member integrating components corresponding to the outer pipe main body 11, inlet pipe 17, and outlet pipe 16 described above. The outer pipe main body 31 includes an inlet pipe portion 311 (primary pipe) on one side, a main pipe portion 312 continuous with the inlet pipe portion 311, and an outlet pipe portion 313 continuous with the main pipe portion 312. The inlet pipe portion 311 corresponds to the inlet pipe 17 described above. The main pipe portion 312 accommodates a valve main body 32 having a valve seat main body 33 and a valve holder 34 therein. The valve holder 34 accommodates a valve element 35. The outlet pipe portion 313 corresponds to the outlet pipe 16 described above.

[0059] Fixing portions 312a that deform radially inward to fix the valve seat main body 33 are formed at four locations on the circumferential surface of one side X1 of the main body pipe portion 312. These fixing portions 312a are crimped and deformed by a punch of a press device so as to bite into annular recessed portions 332c (described later) of the valve seat main body 33, thereby fixing the valve seat main body 33 at a predetermined position inside the main body pipe portion 312.

[0060] The valve seat main body 33 is press-fitted axially into one side X1 of the main body pipe portion 312. The valve seat main body 33 is formed by cutting or the like using a metal material such as stainless steel. The valve seat main body 33 has a valve seat portion 331 on the other side X2 and a tubular portion 332 on one side X1.

[0061] The valve seat 331 is formed in a stepped shape recessed toward one side X1, and the surface facing the other side X2 forms a flat contact surface 331a on which the valve body 35 is seated. A valve port 331b that opens in the axial direction is formed in the center of the valve seat 331.

[0062] The cylindrical portion 332 is a portion that extends toward the one side X1, continuing from the valve port 331b, and has an inlet opening 332a that opens toward the one side X1 at its end on the one side X1. That is, the inlet opening 332a is continuous with the cylindrical portion 332 and opens toward the one side X1. The inner diameter of the inlet opening 332a is larger than the inner diameter of the valve port 331b and is set to be the same as the inner diameter of the inlet pipe portion 311. Therefore, the inner diameter of the cylindrical portion 332 decreases from the inlet opening 332a toward the valve port 331b, and the inner circumferential surface 332b of the cylindrical portion 332 is formed with a taper at a predetermined inclination angle θ from the inlet opening 332a to the valve port 331b. The value of the predetermined inclination angle θ is set similarly to the first embodiment. The circumferential surface of the cylindrical portion 332 is formed with an annular recess 332c that deforms radially inward at a position corresponding to the fixing portion 312a.

[0063] As described above, the check valve 3 includes the valve holder 34 and the valve element 35. The valve holder 34 corresponds to the above-described valve holder 14, and the valve element 35 corresponds to the above-described valve element 15, and since they have the same structure, their description will be omitted in the description of the check valve 3 of the third embodiment.

[0064] In this check valve 3 in which the inlet pipe portion 311 and the outlet pipe portion 313 are integrated, the inclination angle θ of the inner circumferential surface 332b of the tubular portion 332 was set to 20°, and the above-mentioned Cv value was calculated. The result was 114.2 points, compared to the Cv value of 100% when the inclination angle θ of the first embodiment (i.e., a structure in which the components corresponding to the inlet pipe portion 311 and the outlet pipe portion 313 are not integrated) is 180°. This means that the Cv value was improved by up to 14.2 points. This configuration allows for a check valve 3 in which the inlet pipe portion 311 and the outlet pipe portion 313 are integrated, with improved sealing performance, reduced Cv value reduction, and reduced size.

[0065] Next, a check valve 3' according to a modified example of the third embodiment will be described. FIG. 7 is an overall cross-sectional view of the check valve 3' according to the modified example of the third embodiment. In the check valve 3', the shape of the inner circumferential surface 332b' of the tubular portion 332 is different from that of the inner circumferential surface 332b described above. The inner circumferential surface 332b' includes a straight portion 332b'-1 extending in the axial direction from the inlet opening 332a toward the other side X2, and a tapered portion 332b'-2 continuing from the straight portion 332b'-1 and extending while reducing in diameter toward the valve port 331b. That is, the inlet opening 332a of the check valve 3' includes the straight portion 332b'-1 extending a predetermined length in the axial direction.

[0066] Even with this configuration, it is possible to obtain a check valve 3' that improves sealing performance, suppresses a decrease in the Cv value, and prevents an increase in size.

[0067] In the above-described embodiments and modified examples, the predetermined inclination angle θ has been described as a constant angle, such as 20° or 30°, but this angle may be a constant angle, may change midway, or may be changed continuously, for example, so that the inner circumferential surface 132b of the tubular portion 132 is arc-shaped.

[0068] The inner circumferential surface 132b is not limited to a tapered or arcuate (R-shaped) shape. In other words, the present invention includes any shape that is smoothly and continuously connected from the inner circumferential surface of the inlet pipe 17 to the inlet opening 132a and from the inner circumferential surface 132b to the valve port 1311b without any steps or the like in the flow path from the inner circumferential surface of the inlet pipe 17 to the valve port 1311b.

[0069] In the second embodiment, even if the corners of the inner circumference of the end face on the other side X2 of the inlet pipe 17 and the corners of the inner circumference of the inlet opening 132a are slightly chamfered or rounded, the same effects and advantages as those of the present invention can be obtained and are included in the present invention.

[0070] In the first and third embodiments, the corners of the inner circumference of the end face on the other side X2 of the inlet pipe 17 and the corners of the inner circumference of the inlet opening 132a both have the same inner diameter and abut without any gap in the direction of the axis X. However, even if both corners are slightly chamfered or rounded, the same functions and effects as those of the present invention can be obtained, and this is included in the present invention. [Explanation of symbols]

[0071] θ Tilt angle X1 One side R1 Inlet opening inner diameter R2 Inner diameter of valve orifice 1. Check valve 1 11 Outer tube body 13 Valve seat body 1311 Valve seat 1311a Contact surface 1311b Benguchi 132 Cylinder part 132a Inlet opening 132b Inner surface 15 Valve body 151c-1 Contact surface

Claims

1. A check valve comprising: an outer pipe portion extending in an axial direction; a valve seat body provided so as to dispose a valve seat portion inside the outer pipe portion; and a cylindrical valve element capable of abutting against the valve seat portion at flat abutment surfaces, the check valve being installed midway along a fluid flow path in a closed circuit system, the valve seat body has a valve port that opens to the valve seat portion, a hollow cylindrical portion that is continuous with the valve port and extends to one side in the axial direction, and an inlet opening that is continuous with the cylindrical portion and opens to the one side, The valve port has an inner diameter smaller than the inner diameter of the inlet opening, the inner circumferential surface of the cylindrical portion is formed to have a taper at a predetermined inclination angle from the inlet opening to the valve port, and is continuous with the inner circumferential surface of the valve port without any steps; the inclination angle is between 10° and 45°; The axial length of the cylindrical portion is greater than half the inner diameter of the valve port, the valve element is provided slidably in the axial direction relative to the valve seat body, A check valve characterized in that a plurality of grooves extending in the axial direction are provided on the outer peripheral surface of the valve body.

2. the outer pipe portion includes a primary pipe communicating with the inlet opening; 2. The check valve according to claim 1, wherein the inner diameter of the inlet opening is set to be the same as the inner diameter of the primary pipe.

3. the outer pipe portion includes a primary pipe communicating with the inlet opening; 3. The check valve according to claim 1, wherein the axial length of the cylindrical portion is greater than the axial length of the valve port.

4. 4. The check valve of claim 3, wherein a gap is provided between the inlet opening and an edge of the primary pipe.

5. 4. The check valve according to claim 3, wherein the inlet opening has a straight portion extending a predetermined length in the axial direction.

6. A refrigeration cycle system comprising the check valve according to claim 3.

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