JP7808019B2 - Check valve and refrigeration cycle system - Google Patents

Description

The present invention relates to a check valve and a refrigeration cycle system.

A known check valve comprises an outer pipe with 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. Fluid from a primary pipe connected to the outer pipe flows through the valve port to a secondary pipe, and the valve disc closes the valve port to prevent backflow of fluid from the secondary pipe (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), and 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, and the valve seat and valve disc have flat abutment surfaces that abut against each other to close the valve port. 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 on the valve section of the valve disc, and the valve opening is formed with an edge without a tapered surface; the valve opening is closed when the tapered surface abuts on the edge.

Japanese Patent Application Laid-Open No. 2022-19265 JP 2013-44418 A

In a structure in which the valve seat and valve 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 valve disc seats 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 abutting 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, with this structure, the valve seat member must be larger in diameter to make the inner diameter of the valve port the same as the inner diameter of the primary pipe, and the outer pipe surrounds its outer periphery, resulting in a problem in that the check valve becomes larger.

The present invention aims to provide a check valve and refrigeration cycle system that improves sealing performance, suppresses a decrease in Cv value, and prevents the system from becoming larger.

In order to solve the above problems and achieve the object, the check valve of the present invention is a check valve that is installed in the middle of a fluid flow path in a closed circuit system, and includes 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 that can abut against the valve seat portion at their flat abutment surfaces , and 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 inner diameter of the cylindrical portion is smaller than the inner diameter of the inlet opening, the inner peripheral surface of the cylindrical portion is tapered from the inlet opening to the valve opening at a predetermined inclination angle and is continuous with the inner peripheral surface of the valve opening without any steps, the inclination angle is 10° to 45°, the axial length of the cylindrical portion is greater than half the inner diameter of the valve opening, the valve body is slidable in the axial direction relative to the valve seat body, and the outer peripheral surface of the valve body is provided with a plurality of grooves extending in the axial direction .

According to the present invention, the valve disc and valve seat abut against each other via flat abutment surfaces. This makes it less likely for the valve disc to tilt when seated, compared to conventional structures with the tapered/edge seal structure described above, 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 any 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, minimizes a decrease in Cv value, and prevents the valve from becoming larger.

In this case, it is preferable that the outer tube portion includes a primary pipe communicating with the inlet opening, and that the inner diameter of the inlet opening be set to the same diameter as the inner diameter of the primary pipe. With this configuration, there is no step between the primary pipe and the inlet opening, which allows for a smoother flow of fluid between the primary pipe and the inlet opening, improving the Cv value.

Furthermore, it is 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.

A gap may also be provided between the inlet opening and the edge of the primary pipe. With this configuration, even when a gap exists 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 the Cv value, and prevents the valve from becoming too large.

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

The refrigeration cycle system of the present invention is characterized by including any of the check valves described above. With this configuration, a refrigeration cycle system can be constructed using a check valve that improves sealing performance, suppresses a decrease in the Cv value, and prevents the check valve from becoming larger.

The present invention provides a check valve and refrigeration cycle system that improves sealing performance, suppresses a decrease in Cv value, and prevents the system from becoming larger.

1 is an overall cross-sectional view of a check valve according to a first embodiment of the present invention; FIG. 2 is an enlarged cross-sectional view of the valve seat body in FIG. 1 . FIG. 4 is a diagram showing a Cv value simulation graph of the check valve according to the first embodiment. FIG. 4 is an overall cross-sectional view of a check valve according to a modified example of the first embodiment. FIG. 10 is an overall cross-sectional view of a check valve according to a second embodiment. FIG. 11 is an overall cross-sectional view of a check valve according to a third embodiment. FIG. 11 is an overall cross-sectional view of a check valve according to a modified example of the third embodiment. A refrigeration cycle system equipped with a check valve shown in any one of Figures 1 to 7.

The check valve 1 according to the 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 midway through the 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 also composed of a valve seat body 13 and a valve holder 14.

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

The outer pipe body 11 is a cylindrical member extending in the axial direction, and is formed by cutting or other processes 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. The end of one side X1 of a copper outlet pipe 16 (secondary pipe) connected to piping (not shown) is inserted toward the open end of the other side X2 of the outer pipe body 11, and in this state is connected by brazing or other processes.

As described above, the valve body 12 comprises the valve seat body 13 and the valve holder 14. The valve seat body 13 is a generally cylindrical portion provided on one side X1 of the outer pipe body 11, and is formed by cutting or other processes using a metal material such as stainless steel.

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 connected to the end of the outer pipe body 11 on one side X1, and its outer diameter is smaller than that of the rest of the valve seat body 13. The outer peripheral surface of the reduced diameter portion 131 is fitted into the inner peripheral surface of the outer pipe body 11. In this state (i.e., when disposed within 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 1311. In other words, a portion of the valve seat portion 1311 is disposed within 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 seats. A valve port 1311b that opens in the axial direction is formed in the center of the valve seat 1311. The radial position of the abutment surface 1311a is set toward the axis X (toward the radial center axis) to take advantage of the difference between the inner diameter R1 of the inlet opening 132a (described below) and the inner diameter R2 of the valve port 1311b, which makes it difficult for the valve seat body 13 to be larger in the radial direction than the inlet pipe 17 (described below).

The tubular portion 132 is a cylindrical portion that continues from the valve opening 1311b and extends toward the one side X1. 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 is continuous with the tubular 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 the same diameter as the inner diameter R3 of the inlet pipe 17 (primary pipe) described below. Therefore, the inner diameter of the tubular portion 132 decreases from the inlet opening 132a toward the valve opening 1311b. As a result, the inner circumferential surface 132b of the tubular portion 132 is tapered at a predetermined inclination angle θ from the inlet opening 132a to the valve opening 1311b.

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

If the tubular portion 132 is not provided, the inner circumferential surface 132b will not be tapered. Therefore, due to the difference between the inner diameter R1 of the inlet opening 132a and the inner diameter R2 of the valve opening 1311b, a step will be created between the inlet opening 132a and the valve opening 1311b, and the inclination angle θ will be essentially 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. For this reason, it is preferable to set the predetermined inclination angle θ of the tapered inner circumferential surface 132b of the tubular portion 132 to 45° or less, for example, in order to achieve the effects described below. In the first embodiment, the inclination angle θ shown in Figures 1 and 2 is 20°.

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 smaller 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 half the inner diameter R2 of the valve opening 1311b.

As mentioned above, because the inner diameter R1 of the inlet opening 132a is 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 and processing costs of the tubular portion 132, so it is more preferable to set the inclination angle θ to 10° or greater.

The connecting portion 133 is a cylindrical portion that continues from the tubular portion 132, extends to 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 stepped portion 133b that is recessed toward the other side X2 is formed between the inner circumferential surface 132b of the tubular portion 132 and the inner circumferential surface 133a of the connecting portion 133. The end 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 stepped portion 133b, and is fixed in this state by brazing or the like.

Like the outlet pipe 16, the inlet pipe 17 is made of copper, 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 tubular portion 132 are continuous without any steps, and the inlet pipe 17 is in communication with the inlet opening 132a.

The valve holder 14 is the portion of the outer pipe body 11 that houses the valve disc 15. As shown in FIG. 1, it is cylindrical and extends 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 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 connecting the interior of the valve holder 14 to 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 surface of the end of the other side X2 of the valve holder 14. The valve stopper 18 is a retaining ring that prevents the valve disc 15 from moving toward the other side X2 when it abuts against it, and determines the extreme position of the valve disc 15's movement toward the other side X2.

The valve element 15 is a resin member that is axially slidable within the valve holder 14 of the valve body 12. The valve element 15 has four axially extending grooves 151a in the approximately cylindrical valve element body 151, and is formed so that the cross section intersecting the axial direction is approximately cross-shaped. The formation of the grooves 151a reduces the resistance to movement of the valve element 15 relative to the valve holder 14 around the axis X, allowing the valve element 15 to slide smoothly.

A lightening portion 151b is formed in the center of the valve body 151 of the valve body 15, which is lightened so that it does not penetrate from the center of the end face on the other side X2 to the one side X1. This lightening portion 151b suppresses the occurrence of sink marks and air bubbles during resin molding of the valve body 15 and contributes to reducing the weight of the valve body 15. The end on the one side X1 of the valve body 151 forms the bottom plate portion 151c of the valve body 151, and the outer peripheral edge of the bottom plate portion 151c forms the 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 mutually flat abutment surfaces 1311a and 151c-1.

The check valve 1 configured in this manner can be used in a variety of positions. For example, when the axial direction shown in Figure 1 is vertical, i.e., when used in a vertically installed position, it operates as follows. First, when the valve disc 15 is seated on the valve seat 1311 and in the position shown in Figure 1 (hereinafter also referred to as the valve closed position), fluid flows in the forward direction from the inlet pipe 17 to the outlet pipe 16. Then, the valve disc 15 is pushed by the fluid flowing out of the valve port 1311b and moves to a position where it abuts the valve stopper 18 (hereinafter also referred to as the valve open position). Then, when the flow of fluid in the forward direction stops, the valve disc 15 falls under its own weight and once again seats on the valve seat 1311.

When the check valve 1 is used horizontally or upside down, it operates as follows. First, when the valve disc 15 is in the closed position, the pressure on the outlet pipe 16 side is set higher than on the inlet pipe 17 side, and the differential pressure at this time presses the valve disc 15 against the valve seat 1311, maintaining the seated state. In this state, when fluid flows in the forward direction from the inlet pipe 17 side to the outlet pipe 16 side, the valve disc 15 is pressed by the fluid flowing out of the valve port 1311b and moves to the open position. Then, when the forward flow of fluid stops and the pressure on the outlet pipe 16 side becomes higher than on the inlet pipe 17 side, the differential pressure causes the valve disc 15 to reseat on the valve seat 1311.

As shown in Figure 8, this check valve 1 is installed midway through the refrigerant flow path in a refrigeration cycle system 50. Refrigeration cycle system 50 is used, for example, in air conditioners such as commercial air conditioners. 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 via piping. To prevent backflow of refrigerant to each compressor 55, 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.

During cooling operation, as indicated 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 dissipating heat in outdoor heat exchanger 52, it flows through expansion valve 53 to indoor heat exchanger 51. After absorbing heat in indoor heat exchanger 51, it returns to compressor 55 via four-way valve 54. During heating operation, as indicated 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 dissipating heat in indoor heat exchanger 51, it flows through expansion valve 53 to outdoor heat exchanger 52. After absorbing heat in outdoor heat exchanger 52, it returns to compressor 55 via four-way valve 54. The refrigeration cycle system 50 repeats these cycles to cool or heat the room.

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. Also, 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 closing the two check valves 1.

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 a capacity coefficient, will be explained using 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 flow.

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. However, the numerical values of the calculation conditions are merely examples, and similar effects can be achieved by changing the respective numerical values in a similar manner depending on the size of the check valve. Note that 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.

In Figure 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 improves linearly when the inclination angle θ is in the range of 150° to 45°. Specifically, when the Cv value when the inclination angle θ is 180° is used as the reference, the Cv value improved by up to 15.6 points when the inclination angle θ is 45° or less.

In addition, in conventional check valve structures, 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 possible to improve the Cv value by chamfering the corners of this step so that the inclination angle θ is approximately 90°, for example. 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.

On the other hand, in the range of 45° to 10°, the Cv value increased slightly. Here, as mentioned above, the smaller the inclination angle θ, the longer the axial length L1 of the inner circumferential surface 132b needs to 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 have a shorter 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°.

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 conventional structures equipped 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. Therefore, the Cv value can be improved compared to conventional structures 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, preventing the outer diameter of the valve seat body 13 from becoming larger. This makes it possible to obtain a check valve that improves sealing performance, prevents a decrease in the Cv value, and prevents the valve from becoming larger.

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 the same diameter, which eliminates any step 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.

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 compared to a Cv value of 100% when the inclination angle θ is 180°, and by up to 6.3 points when compared to a Cv value of 100% when the inclination angle θ is 90°.

Furthermore, according to this embodiment, a refrigeration cycle system 50 can be constructed using a check valve 1 that improves sealing performance, suppresses a decrease in the Cv value, and prevents the system from becoming larger.

The first embodiment described above merely illustrates a typical form of the present invention, and the present invention is not limited to this. In other words, various modifications can be made without departing from the gist of the present invention. As long as such modifications still include the check valve and refrigeration cycle system configuration of the present invention, they are of course included within the scope of the present invention.

For example, in the first embodiment described above, a check valve 1 used in an air conditioner such as a commercial air conditioner was illustrated. However, the check valve 1 can be used not only in commercial air conditioners but also in residential air conditioners, and can be applied 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 within the various refrigeration cycle systems. Furthermore, there are a wide variety of refrigerants available for each refrigeration cycle system (e.g., 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 refrigeration cycle systems compatible with any of these refrigerants.

Next, a modified example of the first embodiment of the present invention will be described. Figure 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 outlet pipe 16 described above, differs from that of the first embodiment. The outlet pipe 16' comprises a connecting pipe section 161 connected to the other side X2 of the outer pipe main body 11, a reduced diameter pipe section 162 that continues from the connecting pipe section 161 and extends to the other side X2 and has a reduced diameter, and an expanded diameter section 163 that continues from the reduced diameter pipe section 162 and extends to the other side X2 and has 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 described above can be obtained.

Next, a check valve 2 according to a second embodiment of the present invention will be described. Figure 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 body 23, which corresponds to the valve seat body 13 described above. The valve seat body 23 includes a second step portion 231 recessed toward the other side X2, between the inlet opening 132a and a step portion 133b against which the end of the inlet pipe 17 on the other side X2 abuts. This forms an axial gap 232 between the edge of the other side X2 of the inlet pipe 17 connected to the valve seat body 23 and the inlet opening 132a. This gap 232 functions as a brazing reservoir when brazing the inlet pipe 17 to the valve seat body 23.

The way in which the brazing fills the gap 232 as a brazing fill area is not consistent; sometimes the gap 232 is completely filled, and sometimes it is barely filled at all. The way the brazing fills also varies depending on the size of the gap 232.

In general, providing a gap 232 that may not be filled with brazing filler would likely result in fluid remaining in the gap 232, increasing pressure loss and making it difficult for the fluid to flow. However, in the second embodiment, the inclination angle θ of the inner circumferential surface 132b of the tubular portion 132 was set to 20°, and the above-mentioned Cv value was calculated for a gap with no brazing filler. When the Cv value of 100% was calculated for the first embodiment (i.e., a structure without gap 232) with an inclination angle θ of 180°, the result was 113.7%, improving the Cv value by up to 13.7 points. While this Cv value is slightly smaller than the Cv value of 115.6% when the inclination angle θ is 20° shown in Figure 3 (i.e., when the inclination angle θ in the structure of the first embodiment is 20°), it is significantly larger than when the inclination angle θ is 180°. Thus, an improvement in the Cv value was observed in the second embodiment as well.

The reason why an improvement in the Cv value is observed even when a gap 232 is present is that the inner diameter of the inlet pipe 17 and the inner diameter of the inlet opening 132a are the same, so even when a gap 232 is present, there are no steps or other obstacles that act as barriers to the fluid's straight-line flow. As a result, the fluid flows straight from the inlet pipe 17 along the inner circumference of the inlet pipe 17 in the direction of the other side X2, and then flows smoothly along the inner surface of the inlet opening 132a.

According to the present invention, even when a gap 232 exists between the inlet opening 132a and the edge of the inlet pipe 17, it is possible to obtain a check valve 2 that improves sealing performance, suppresses a decrease in the Cv value, and prevents the valve from becoming too large.

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 the outer portions that make up the check valves 1, 1', and 2, and this entirety is collectively referred to as the "outer pipe portion" in the present invention. Note that in the first and second embodiments described above, the outer pipe body 11 and the valve seat body 13 are not fixed together by laser welding or the like, and these two components may be formed as a single, integrated structure. Furthermore, the check valve may be configured by sandwiching a connecting member or other 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.

In the first and second embodiments, the other side X2 portion of the valve seat body 13 is fixed to the one side X1 end of the outer pipe body 11 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. Therefore, in the above explanation, it was said that only a portion is located. However, as described above, the tubular portion 132 can also be considered an outer pipe portion (i.e., the tubular portion 132 can constitute part of the outer pipe portion), and therefore the valve seat portion 1311, which is integral with the outer pipe portion, can be said to be located inside the outer pipe body 11 and tubular portion 132 portion as the outer pipe portion.

However, this configuration is not limited to this, and as shown in the third embodiment described below, 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 components). In other words, 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 positioned inside the outer pipe portion.

Next, a check valve 3 according to a third embodiment of the present invention will be described. Figure 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 body 31. The outer pipe body 31 of the third embodiment corresponds to the "outer pipe portion" of the third embodiment and is configured as an integrally molded copper member that integrates components corresponding to the outer pipe body 11, inlet pipe 17, and outlet pipe 16 described above. The outer pipe body 31 includes an inlet pipe portion 311 (primary pipe) on one side, a main pipe portion 312 that continues from the inlet pipe portion 311, and an outlet pipe portion 313 that continues from the main pipe portion 312. The inlet pipe portion 311 corresponds to the inlet pipe 17 described above. The main pipe portion 312 houses a valve body 32 that has a valve seat body 33 and a valve holder 34 inside. The valve holder 34 houses a valve element 35. The outlet pipe portion 313 corresponds to the outlet pipe 16 described above.

Fixing portions 312a are formed at four locations on the circumferential surface of one side X1 of the main body pipe portion 312, deforming radially inward to secure the valve seat body 33. These fixing portions 312a are crimped and deformed by a punch in a press device so as to bite into the annular recess 332c (described below) of the valve seat body 33, thereby securing the valve seat body 33 in a predetermined position inside the main body pipe portion 312.

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

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

The cylindrical portion 332 extends toward the X1 side, continuing from the valve port 331b. An inlet opening 332a is formed at the end of the X1 side, opening toward the X1 side. That is, the inlet opening 332a is continuous with the cylindrical portion 332 and opens toward the X1 side. The inner diameter of the inlet opening 332a is larger than the inner diameter of the valve port 331b and is set to the same diameter 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. As a result, the inner circumferential surface 332b of the cylindrical portion 332 tapers 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 in the same way as in 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.

As described above, the check valve 3 comprises a valve holder 34 and a valve element 35. The valve holder 34 corresponds to the valve holder 14 described above, and the valve element 35 corresponds to the valve element 15 described above. Since their structures are the same, they will not be described in the description of the check valve 3 of the third embodiment.

When the above-mentioned Cv value was calculated for a check valve 3 in which the inlet pipe section 311 and outlet pipe section 313 are integrated, with the inclination angle θ of the inner peripheral surface 332b of the tubular section 332 set to 20°, the result was 114.2 points, compared to a 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 section 311 and outlet pipe section 313 are not integrated), which is 180°. This means that the Cv value was improved by a maximum of 14.2 points. This configuration allows for a check valve 3 in which the inlet pipe section 311 and outlet pipe section 313 are integrated, with improved sealing performance, reduced Cv value decline, and reduced size.

Next, a check valve 3' according to a modified example of the third embodiment will be described. Figure 7 is an overall cross-sectional view of a check valve 3' according to a modified example of the third embodiment. In the check valve 3', the shape of the inner circumferential surface 332b' of the tubular portion 332 differs from the inner circumferential surface 332b described above. The inner circumferential surface 332b' includes a straight portion 332b'-1 extending axially from the inlet opening 332a toward the other side X2, and a tapered portion 332b'-2 that is continuous with the straight portion 332b'-1 and extends, reducing in diameter, toward the valve opening 331b. In other words, the inlet opening 332a of the check valve 3' includes a straight portion 332b'-1 that extends a predetermined length in the axial direction.

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 the valve from becoming too large.

In the above-described embodiments and variants, the predetermined inclination angle θ has been described as a constant angle, such as 20° or 30°, but this angle may be constant, may change midway, or may change continuously, for example, to make the inner circumferential surface 132b of the tubular portion 132 arc-shaped.

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 smooth and continuous 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 opening 1311b, without any steps or other differences in the flow path.

In the second embodiment, even if the corners of the inner periphery of the end face on the other side X2 of the inlet pipe 17 and the corners of the inner periphery 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.

In addition, 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 are included in the present invention.

θ Tilt angle X1 One side R1 Inner diameter of inlet opening R2 Inner diameter of valve port 1 Check valve 1
11 Outer tube body 13 Valve seat body 1311 Valve seat portion 1311a Contact surface 1311b Valve port 132 Cylindrical portion 132a Inlet opening 132b Inner peripheral surface 15 Valve body 151c-1 Contact surface

Claims (6)

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 . 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. 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. A check valve as described in claim 3, characterized in that a gap is provided between the inlet opening and the edge of the primary pipe. A check valve as described in claim 3, characterized in that the inlet opening has a straight portion extending a predetermined length in the axial direction. A refrigeration cycle system equipped with the check valve described in claim 3.