JP2019100666A - Relief valve - Google Patents

Abstract

To provide a relief valve which can maintain the performance of sealing a refrigerant over a long time use, and can maintain a constant valve-opening pressure of a valve body.SOLUTION: A valve case 100 is attached into an attachment hole which is formed at a high-pressure side constituent member of a refrigeration cycle, and has a flow passage 111 for making a refrigerant flow and a valve seat 122 arranged in the middle of the flow passage. The valve case 100 is made of metal. The valve seat 13 is accommodated in the flow passage 111 of the valve case 100, and arranged so as to be seated and separated to/from the valve seat 122. A spring as a biasing member biases the valve body 13 to the valve seat 122 side by a prescribed biasing force. As resin coatings 17, 18, a resin whose regular heat resistance temperature is higher than a temperature of a high-pressure refrigerant of the refrigeration cycle is provided at least on either of a surface of the valve seat 122 or a surface of the valve body 13.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a relief valve provided in a refrigeration cycle.

  Conventionally, when the pressure of the refrigerant circulating in the refrigeration cycle becomes an abnormally high pressure, a relief valve is known which discharges the refrigerant from the refrigeration cycle to the atmosphere to prevent damage or the like of each device constituting the refrigeration cycle.

  The relief valve described in Patent Document 1 includes a cylindrical valve case and a valve body housed inside the valve case. The valve body is provided so as to be able to be seated and separated from a valve seat provided on the inner wall of the flow passage inside the valve case. A rubber packing is fixed to the valve body at a portion that abuts on the valve seat. The relief valve secures the seal between the valve seat and the valve body by its rubber packing.

  Further, the relief valve described in Patent Document 1 includes an O-ring on the outside of the valve case. The valve case is fixed to a component on the high pressure side of the refrigeration cycle via the O-ring. The relief valve secures sealing between the component on the high pressure side of the refrigeration cycle and the valve case by the O-ring.

  On the other hand, the relief valve described in Patent Document 2 has a configuration in which a valve seat member having a valve seat and a spherical valve body that is seated on and away from the valve seat are both made of metal only.

Patent No. 3292796 gazette Patent Application Publication FR 2 998 430 A1

  The inventor has found a new problem with the relief valve described in Patent Documents 1 and 2 described above. That is, in the relief valve described in Patent Document 1, since the thickness of the rubber packing fixed to the valve body is large, when the rubber packing is elastically deformed, the biasing force of the spring which biases the valve body toward the valve seat (ie , Spring force) changes. Therefore, this relief valve has a problem that the valve opening pressure (that is, the valve opening set load) of the valve can not be maintained constant over long-term use.

  On the other hand, in the relief valve described in Patent Document 2, the valve seat and the valve body are formed only of metal. Therefore, there is a problem that the refrigerant leaks to the atmosphere from a slight gap between the valve seat and the valve body.

By the way, in recent years, from the viewpoint of environmental protection, development of a refrigeration cycle using carbon dioxide (hereinafter referred to as CO ₂ ) as a refrigerant has been advanced. The operating pressure of the refrigeration cycle using this CO ₂ refrigerant is 4 to 7 times that of the refrigeration cycle using a fluorocarbon refrigerant such as HFC-134a. Therefore, the biasing force of the spring that biases the valve body of the relief valve toward the valve seat must be set large, and the valve opening pressure of the valve body must be set high. Generally, the valve opening pressure of the valve body is set to 1.2 times or more of the operating pressure of the refrigeration cycle. When the relief valve described in Patent Document 1 is applied to a refrigeration cycle using such a CO ₂ refrigerant, the fluctuation of the valve opening pressure of the valve body is accompanied by the elastic deformation of the rubber packing fixed to the valve body. growing.

Also, the case of applying the relief valve according to a refrigeration cycle using CO ₂ refrigerant in Patent Document 1, since CO ₂ refrigerant is a small molecular weight, rubber packing and fixed to the valve body, is provided outside the valve case The problem of passing through the O-ring and leaking to the atmosphere arises.

Furthermore, as described above, since the operating pressure of the refrigeration cycle using the CO ₂ refrigerant is higher than the operating pressure of the refrigeration cycle using the fluorocarbon refrigerant, the temperature of the CO ₂ refrigerant flowing along the high pressure side of the refrigeration cycle is high. Become. Therefore, when the relief valve described in Patent Document 1 is applied to a refrigeration cycle using a CO ₂ refrigerant, the rubber packing fixed to the valve body and the O-ring provided on the outside of the valve case thermally deteriorate, and CO ₍₂₎ There is also a problem that the refrigerant leaks to the atmosphere.

In addition, in order to improve the sealing property of the valve seat of a relief valve, and a valve body, it is possible to form either a valve seat or a valve body only with resin. However, in that case, the relief valve applied to the refrigeration cycle using a CO ₂ refrigerant is used under a high temperature and heavy load environment, so when the resin is creep-deformed, the sealability between the valve seat and the valve body is It can not be maintained, and the valve opening pressure of the valve body may change.

  Furthermore, in order to improve the sealability between the valve seat of the relief valve and the valve body, there is also known a technique of applying soft tin plating to either the surface of the valve seat or the surface of the valve body (Japanese Patent Laid-Open No. 2005-214396) Issue). However, in this case, if the relief valve is opened once by inspection at the factory, etc., the tin plating may peel off from the valve seat or the valve body, and the sealing performance may deteriorate and the valve opening pressure of the valve body may change. There is. Thus, with any of the above-described configurations, it is difficult to maintain the hermeticity of the refrigerant over the long-term use of the relief valve and to keep the valve opening pressure constant.

  An object of the present invention is, in view of the above-mentioned point, to provide a relief valve capable of maintaining the sealing property of the refrigerant for long-term use and maintaining the valve opening pressure of the valve body constant.

In order to achieve the above object, the invention according to claim 1 relates to a relief valve for releasing the refrigerant from the refrigeration cycle when the refrigerant pressure of the refrigeration cycle (1) becomes an abnormally high pressure,
It has a flow passage (111, 121) attached to a mounting hole (22) provided in a component on the high pressure side of the refrigeration cycle, and a valve seat (122) provided in the middle of the flow passage Metal valve cases (11, 12, 100),
A valve body (13) accommodated in the flow path of the valve case and provided so as to be able to sit and leave the valve seat;
An urging member (14) for urging the valve body toward the valve seat with a predetermined urging force;
And a resin coating (17, 19) formed of a resin having a commonly used heat resistant temperature higher than the temperature of the high pressure refrigerant of the refrigeration cycle and provided on at least one of the surface of the valve seat or the surface of the valve body.

  According to this, by applying a thin resin coating to the surface of the valve seat or the surface of the valve body of the metal valve case, the valve seat and the valve are protected against the high load of the high pressure refrigerant and the biasing member. It is possible to keep the setting position with the body constant over long-term use. Therefore, the biasing force by the biasing member is kept constant. Therefore, this relief valve can maintain the valve opening pressure of the valve body constant over long-term use.

Also, by using a resin for the coating applied to the surface of the valve seat or the surface of the valve body, for example, even when a low molecular weight CO ₂ refrigerant is used, it is possible to prevent the CO ₂ refrigerant from permeating the coating. It is possible. Furthermore, by using a resin having a commonly used heat-resistant temperature higher than the temperature of the high-pressure refrigerant in the refrigeration cycle for coating, for example, even when using a CO ₂ refrigerant having a high operating pressure, thermal degradation of the coating can be prevented. is there. Therefore, this relief valve can maintain the hermeticity of the refrigerant over long-term use.

  In addition, the code | symbol in the parenthesis attached | subjected to each said structure shows an example of the correspondence with the specific structure described in embodiment mentioned later.

It is a figure which shows the cross-sectional structure of the relief valve which concerns on 1st Embodiment. It is an enlarged view of II part of FIG. It is a schematic diagram of the refrigerating cycle to which a relief valve is applied. It is a graph which shows the optimal range of the bending elastic modulus of resin coating. It is a graph which shows the optimal range of the film thickness of resin coating. It is a figure showing the section composition of the relief valve concerning a 2nd embodiment. It is an enlarged view of VII part of FIG. It is a figure which shows the cross-sectional structure of the relief valve which concerns on 3rd Embodiment. It is an enlarged view of IX part of FIG. It is a figure which shows the cross-sectional structure of the relief valve which concerns on 4th Embodiment. It is an enlarged view of XI part of FIG. It is a figure which shows the cross-sectional structure of the relief valve which concerns on 5th Embodiment. It is an enlarged view of XIII part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts identical or equivalent to each other are given the same reference numerals, and descriptions thereof will be omitted.

First Embodiment
A first embodiment will be described with reference to the drawings. The relief valve of the present embodiment is applied to a refrigeration cycle that constitutes a vehicle air conditioner. The relief valve discharges the refrigerant from the refrigeration cycle to the atmosphere when the pressure of the refrigerant circulating in the refrigeration cycle becomes an abnormally high pressure, thereby preventing damage or the like of each device constituting the refrigeration cycle.

First, the configuration of a refrigeration cycle to which the relief valve of the present embodiment is applied will be described. As shown in FIG. 3, the refrigeration cycle 1 is configured by connecting a compressor 2, a radiator 3, an expansion valve 4, an evaporator 5 and the like in a ring shape by a refrigerant pipe 6. The refrigeration cycle 1 of the present embodiment employs carbon dioxide (hereinafter referred to as CO ₂ ) as a refrigerant. The refrigeration cycle 1 is a supercritical refrigeration cycle in which a CO ₂ refrigerant is used at a pressure above the critical point.

The compressor 2 is driven by transmitting power from the engine 7 of the vehicle via the belt 8 and the like. The compressor 2 discharges the refrigerant sucked from the refrigerant pipe 6 on the evaporator 5 side at a high pressure. The compressor 2 can compress the CO ₂ refrigerant to a pressure above the critical point. The operating pressure of the CO ₂ refrigerant compressed by the compressor 2 is 4 to 7 times the operating pressure of the refrigeration cycle 1 using a fluorocarbon refrigerant such as HFC-134a, and along with that, the refrigerant temperature on the high pressure side is also Get higher.

  The radiator 3 radiates the refrigerant discharged from the compressor 2. The expansion valve 4 decompresses and expands the refrigerant flowing out of the radiator 3. The evaporator 5 evaporates and evaporates the refrigerant decompressed and expanded by the expansion valve 4. The air conditioning unit for vehicles which is not shown in figure cools the air ventilated to a vehicle interior by the vaporization heat of the refrigerant | coolant which evaporates with the evaporator 5. As shown in FIG. The refrigerant evaporated by the evaporator 5 is drawn into the compressor 2.

  As shown in FIGS. 1 to 3, the relief valve 10 of the present embodiment is attached to a housing 21 of the compressor 2. The relief valve 10 releases the refrigerant from the refrigeration cycle 1 to the atmosphere at a pressure equal to or less than the pressure resistance of each device constituting the refrigeration cycle 1 when the refrigerant pressure circulating in the refrigeration cycle 1 is abnormally high. Thereby, the relief valve 10 can prevent damage or the like of each of the devices constituting the refrigeration cycle 1. The housing 21 of the compressor 2 corresponds to an example of a component on the high pressure side of the refrigeration cycle 1.

  Next, the configuration of the relief valve 10 of the present embodiment will be described with reference to FIGS. 1 and 2. The housing 21 of the compressor 2 is provided with a mounting hole 22 for mounting the relief valve 10. The mounting hole 22 communicates with a discharge chamber (not shown) through which the high-temperature and high-pressure refrigerant compressed by the compressor 2 flows, through the communication passage 23. A female screw 24 is formed on the side surface of the inner wall of the mounting hole 22.

  The relief valve 10 includes a valve case 100, a valve body 13, a spring 14 as a biasing member, a retainer 15, a stopper 16, and the like.

  The valve case 100 includes a valve case body 11 and a valve seat member 12. The valve case main body 11 is formed in a tubular shape, and has a flow path 111 for flowing the refrigerant inside. An external thread 112 is formed on the radially outer side of the valve case body 11. The valve case main body 11 is fixed to the mounting hole 22 of the housing 21 by screwing the male screw 112 of the valve case main body 11 with the female screw 24 provided in the mounting hole 22 of the housing 21 of the compressor 2.

  A concave portion 113 is provided on the bottom surface 221 side of the mounting hole 22 in the valve case main body 11. The inner diameter of the recess 113 is larger than the inner diameter of the flow passage 111 of the valve case body 11. Therefore, a step surface 114 is formed at the boundary between the flow passage 111 and the recess 113 of the valve case main body 11.

  Inside the recess 113 of the valve case main body 11, the valve seat member 12 is fixed. The valve seat member 12 is in contact with the step surface 114 of the valve case body 11. Thereby, the valve case main body 11 and the valve seat member 12 are positioned. In that state, the valve case main body 11 and the valve seat member 12 are fixed by caulking, heat caulking, press fitting, or the like.

  The valve seat member 12 is formed in a tubular shape, and has a flow passage 121 for flowing the refrigerant inside. The flow passage 111 of the valve case main body 11 and the flow passage 121 of the valve seat member 12 communicate with each other when the valve body 13 is opened. The valve seat member 12 has a valve seat 122 in the middle of the flow path 121 for flowing the refrigerant. The valve seat 122 is formed in a tapered shape in which the inner diameter gradually increases from the bottom surface 221 side of the mounting hole 22 toward the spring 14 side.

  In addition, the valve seat member 12 has an annular protrusion 123 that protrudes annularly toward the bottom surface 221 of the mounting hole 22 on the surface opposite to the valve seat 122. The annular projection 123 is provided to surround the opening of the flow passage 121 of the valve seat member 12.

  As shown in FIG. 2, the valve seat member 12 is coated with a resin coating 17 on the surface on the valve seat 122 side, and is also coated on the surface on the annular protrusion 123 side. The resin coatings 17 and 18 are provided on the entire surface of the valve seat 122 and the entire bottom surface of the mounting hole 22 including the annular projection 123 in the valve seat member 12. However, the resin coating 17 applied to the surface on the valve seat 122 side may be applied at least to the surface of the portion of the valve seat 122 to which the valve body 13 abuts. In addition, the resin coating 18 applied to the surface on the side of the annular protrusion 123 may be applied at least to the surface of a portion of the annular protrusion 123 that abuts on the bottom surface 221 of the mounting hole 22. In the present embodiment, the resin coating is not provided on the valve body 13.

  The resin coatings 17 and 18 are formed of a resin having a commonly used heat resistant temperature higher than the temperature of the high pressure refrigerant of the refrigeration cycle 1. For example, engineering plastics such as polyamide (PA) or super engineering plastics such as polyimide (PI), polyamide imide (PAI), and polyether ether ketone (PEEK) can be adopted as the resin coatings 17 and 18, respectively. is there. In addition, the optimal range of the bending elastic modulus of resin coating 17 and 18, and the optimal range of the film thickness are mentioned later.

The valve case body 11 and the valve seat member 12 are made of the same kind of metal. Thereby, the linear expansion coefficients of the valve case main body 11 and the valve seat member 12 become the same. Therefore, even if both the valve case main body 11 and the valve seat member 12 are used in a high temperature and high pressure environment, minute deformation or distortion of the valve seat 122 is suppressed by the high temperature and high pressure CO ₂ refrigerant discharged from the compressor 2 Be done. In addition, as a metal which forms the valve case main body 11 and the valve seat member 12, aluminum or copper etc. are illustrated.

The valve case body 11 is attached to the mounting hole 22 of the housing 21 in a state in which the valve seat member 12 is fixed to the recess 113 of the valve case body 11. At that time, the annular projection 123 of the valve seat member 12 is pressed against the bottom surface 221 of the mounting hole 22 through the resin coating 18 by an axial force that clamps the male screw 112 of the valve case body 11 into the female screw 24 of the mounting hole 22 of the housing 21 . This prevents the CO ₂ refrigerant from leaking to the atmosphere between the bottom surface 221 of the mounting hole 22 and the valve seat member 12.

  The valve body 13 is accommodated in the flow paths 111 and 121 of the valve case 100. The valve body 13 is, for example, a spherical valve, and is provided so as to be able to be seated and removed from the valve seat 122 of the valve seat member 12. The valve body 13 is formed of, for example, a hard material such as metal or ceramic.

  The surface of the valve body 13 opposite to the valve seat 122 is held by a retainer 15. The radially outer surface of the retainer 15 is in sliding contact with the inner wall of the flow passage 111 of the valve case main body 11. Therefore, the retainer 15 can slide relative to the valve case body 11. A flow passage not shown is provided in a part of the outer wall of the retainer 15.

  A stopper 16 is provided at an end of the valve case main body 11 opposite to the valve seat member 12. The stopper 16 is fixed to the inner wall of the valve case body 11. The stopper 16 is provided with a flow path 161 for releasing the refrigerant from the flow path 111 of the valve case main body 11 to the atmosphere.

A spring 14 as a biasing member is provided between the retainer 15 and the stopper 16. The spring 14 is a compression coil spring, and one end thereof is in contact with the surface of the retainer 15 on the stopper 16 side, and the other end is in contact with the surface of the stopper 16 on the retainer 15 side. The spring 14 biases the valve body 13 against the valve seat 122 via the retainer 15 by a predetermined biasing force. Thereby, the valve body 13 is pressed against the valve seat 122 via the resin coating 17. Therefore, the CO ₂ refrigerant is prevented from leaking to the atmosphere from between the valve body 13 and the valve seat 122. The biasing force of the spring 14 is set so that the valve body 13 is separated from the valve seat 122 at a pressure equal to or less than the pressure resistance of each device constituting the refrigeration cycle 1 when the refrigerant pressure is abnormally high. Specifically, the biasing force of the spring 14 is set to 1.2 times or more of the maximum working pressure of the CO ₂ refrigerant.

  Next, optimum ranges of the flexural modulus and the film thickness of the above-described resin coatings 17 and 18 will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a graph showing the optimum range of the bending elastic modulus (hereinafter simply referred to as “elastic modulus”) of the resin coatings 17 and 18. In FIG. 4, the horizontal axis indicates the elastic modulus of the resin coatings 17 and 18, one vertical axis indicates the airtight pressure (that is, sealability) by the resin coatings 17 and 18, and the other vertical axis indicates the resin coating 17. , 18 break strength (ie, valve load resistance).

  The solid line A in FIG. 4 shows the relationship between the breaking strength and the elastic modulus of the resin coatings 17 and 18. As shown by the solid line A, the breaking strength of the resin coatings 17 and 18 is equal to or higher than the allowable strength when the elastic modulus is 3500 MPa or more. That is, when the elastic modulus of the resin coatings 17 and 18 is set to 3500 MPa or more, the setting position of the valve seat 122 and the valve body 13 is kept constant without breakage of the resin coating 17 by the biasing force of the spring 14. The biasing force by 14 is kept constant. Further, the resin coating 18 is prevented from being broken by an axial force which clamps the male screw 112 of the valve case main body 11 to the female screw 24 of the mounting hole 22. Therefore, the relief valve 10 can maintain the valve opening pressure of the valve body 13 constant over a long period of use.

  The solid line B in FIG. 4 indicates the relationship between the airtight pressure and the elastic modulus by the resin coatings 17 and 18. As indicated by the solid line B, the airtight pressure by the resin coatings 17 and 18 is equal to or higher than the required airtight pressure when the elastic modulus is 5000 MPa or less. That is, when the elastic modulus of the resin coatings 17 and 18 is 5000 MPa or less, the resin coating 17 is slightly deformed by the biasing force of the spring 14 to such an extent that the valve opening pressure of the valve 13 is not affected. Sealability with the body 13 is maintained. Further, since the resin coating 18 is minutely deformed by the axial force which clamps the male screw 112 of the valve case main body 11 to the female screw 24 of the mounting hole 22, the sealing property between the annular projection 123 and the bottom surface 221 of the mounting hole 22 is maintained. Therefore, the relief valve 10 can maintain the hermeticity of the refrigerant over long-term use.

  On the other hand, FIG. 5 is a graph showing the optimum range of the film thickness of the resin coatings 17 and 18. In FIG. 5, the horizontal axis indicates the film thickness of the resin coatings 17 and 18, one vertical axis indicates the airtight pressure (that is, sealability) by the resin coatings 17 and 18, and the other vertical axis indicates the resin coating 17. , 18 creep displacement amount.

  The solid line C in FIG. 5 indicates the relationship between the airtight pressure and the film thickness of the resin coatings 17 and 18. As indicated by the solid line C, the airtight pressure by the resin coatings 17 and 18 is equal to or higher than the required airtight pressure when the film thickness is 20 μm or more. That is, when the film thickness of the resin coatings 17 and 18 is 20 μm or more, the resin coating 17 is slightly deformed by the biasing force of the spring 14 to such an extent that the valve opening pressure of the valve body 13 is not affected. Sealability with the body 13 is maintained. Further, since the resin coating 18 is minutely deformed by the axial force which clamps the male screw 112 of the valve case main body 11 to the female screw 24 of the mounting hole 22, the sealing property between the annular projection 123 and the bottom surface 221 of the mounting hole 22 is maintained. Therefore, the relief valve 10 can maintain the hermeticity of the refrigerant over long-term use.

  The solid line D in FIG. 5 indicates the relationship between the creep displacement amount and the film thickness due to the resin coatings 17 and 18. As shown by the solid line D, when the resin coatings 17 and 18 have a film thickness of 120 μm or less, the deviation amount of the setting value of the biasing force (that is, the spring force) of the spring 14 becomes equal to or less than the allowable value. That is, when the film thickness of the resin coatings 17 and 18 is 120 μm or less, even if the resin coating 17 is slightly creep-deformed by the biasing force of the spring 14, the change in the setting position of the valve seat 122 and the valve body 13 due to that. Is very small. Therefore, the deviation amount of the setting value of the biasing force of the spring 14 does not exceed the allowable value. Therefore, the relief valve 10 can maintain the valve opening pressure of the valve body 13 constant over a long period of use.

The relief valve 10 of the first embodiment described above has the following effects.
(1) In the first embodiment, the resin coating 17 is applied to the surface of the valve seat 122 of the metal valve seat member 12. The resin coating 17 is formed of a resin having a commonly used heat resistant temperature higher than the temperature of the CO ₂ refrigerant on the high pressure side. According to this, it is possible to maintain the setting positions of the valve seat 122 and the valve body 13 for a long time with respect to the high pressure of the CO ₂ refrigerant and the high load of the spring 14. Therefore, the biasing force of the spring 14 is kept constant. Therefore, the relief valve 10 can maintain the valve opening pressure of the valve body 13 constant over a long period of use.

Further, by using a resin for the coating 17 applied to the surface of the valve seat 122, it is possible to prevent the low molecular weight CO ₂ refrigerant from permeating the resin coating 17. Furthermore, it is possible to prevent thermal deterioration of the resin coating 17 by using a resin having a commonly used heat-resistant temperature higher than the temperature of the CO ₂ refrigerant on the high pressure side for coating. Therefore, the relief valve 10 can maintain the hermeticity of the CO ₂ refrigerant over a long period of use.

(2) In the first embodiment, the resin coating 18 is also provided on the surface of the annular projection 123 of the valve seat member 12. According to this, by using a resin for the coating 18 applied to the surface of the annular protrusion 123, it is possible to prevent the low molecular weight CO ₂ refrigerant from transmitting through the resin coating 18. Furthermore, it is possible to prevent the thermal deterioration of the resin coating 18 by using, for the coating, a resin having a commonly used heat resistant temperature higher than the temperature of the high pressure side CO ₂ refrigerant. Therefore, the relief valve 10 can maintain the hermeticity of the refrigerant over long-term use.

  (3) In the first embodiment, the valve case body 11 and the valve seat member 12 are formed of the same type of metal. According to this, the linear expansion coefficients of the valve case main body 11 and the valve seat member 12 become the same. Therefore, even when both the valve case main body 11 and the valve seat member 12 are used in a high temperature and high pressure environment, it is possible to suppress micro deformation or distortion of the valve seat 122. If the valve case main body 11 and the valve seat member 12 are formed of resin, the valve case main body 11 and the valve seat member 12 will be creep-deformed if the valve case main body 11 and the valve seat member 12 are used for a long time under high temperature and high pressure environment. Changes in valve pressure and sealing may occur. On the other hand, by forming the valve case body 11 and the valve seat member 12 of metal and applying the resin coating 17 thereto, the valve body 13 due to the creep deformation of the resin even when used for a long time under a high temperature and high pressure environment. It is possible to prevent the change in the valve opening pressure and the decrease in the sealing performance.

  (4) In the first embodiment, the resin coatings 17 and 18 are provided not on the valve body 13 but on the surface of the valve seat 122 of the valve seat member 12 and the surface of the annular projection 123. According to this, since both the valve seat 122 and the annular projection 123 are provided on the valve seat member 12, it is possible to simplify the process of applying the resin coatings 17 and 18. Further, by applying a thin resin coating 18 to the surface of the annular projection 123 of the metal valve seat member 12, the bottom surface 221 of the mounting hole 22, the valve seat member 12, and the valve case can be used over a long period of use. It is possible to keep the setting position with the main body 11 constant. Therefore, since the biasing force by the spring 14 is kept constant, the valve opening pressure of the valve body 13 is kept constant. Therefore, the relief valve 1 can maintain the valve opening pressure of the valve body 13 constant over a long period of use.

  (5) In the first embodiment, the resin coatings 17 and 18 have a flexural modulus of 3500 to 5000 MPa. According to this, by setting the flexural modulus of the resin coatings 17 and 18 to 3500 MPa or more, the breaking strength of the resin coating 17 against the biasing force of the spring 14 becomes equal to or higher than the allowable strength. And the set position is kept constant. Therefore, since the biasing force by the spring 14 is kept constant over long-term use, the relief valve 10 can maintain the valve opening pressure of the valve body 13 constant. Further, by setting the bending elastic modulus of the resin coatings 17 and 18 to 5000 MPa or less, the resin coating 17 is slightly deformed by the biasing force of the spring 14 to such an extent that the valve opening pressure of the valve body 13 is not affected. It is possible to prevent a gap from occurring between the valve body 13 and the valve body 13. Therefore, the relief valve 10 can maintain the hermeticity of the refrigerant over long-term use.

  (6) In the first embodiment, the resin coatings 17 and 18 have a thickness of 20 to 120 μm. According to this, when the film thickness of the resin coatings 17 and 18 is 20 μm or more, the resin coating 17 is slightly deformed by the biasing force of the spring 14 to such an extent that the valve opening pressure of the valve body 13 is not affected. It is possible to prevent the occurrence of a gap between the seat 122 and the valve body 13. Therefore, the relief valve 10 can maintain the hermeticity of the refrigerant over long-term use. Further, by setting the film thickness of the resin coatings 17 and 18 to 120 μm or less, even when the resin coating 17 is slightly creep-deformed due to the biasing force of the spring 14 or the refrigerant pressure, the setting position of the valve seat 122 and the valve body 13 Change is very small. Therefore, the change of the biasing force of the spring 14 becomes less than the allowable value. Therefore, the relief valve 10 can maintain the valve opening pressure of the valve body 13 constant over a long period of use.

  (7) In the first embodiment, the resin coatings 17 and 18 are engineering plastics or super engineering plastics. According to this, it is possible to make the normal heat resistance temperature of the resin coatings 17 and 18 higher than the temperature of the high pressure refrigerant of the cycle, and to set the flexural modulus of the resin coatings 17 and 18 to 3500 to 5000 MPa.

Second Embodiment
The second embodiment will be described. In the second embodiment, a part of the configuration of the relief valve 10 is modified with respect to the first embodiment, and the other parts are the same as the first embodiment, so only the parts different from the first embodiment are different. explain.

  As shown in FIGS. 6 and 7, the valve case 100 provided in the relief valve 10 of the second embodiment is one in which the valve case main body 11 and the valve seat member 12 described in the first embodiment are integrally formed. is there. The valve case 100 is formed in a tubular shape, and has a flow path 111 for flowing the refrigerant inside, and a valve seat 122 provided in the middle of the flow path 111. Further, the valve case 100 has an annular protrusion 123 that protrudes annularly toward the bottom surface 221 of the mounting hole 22. The annular protrusion 123 is provided to surround the opening of the flow passage 111 of the valve case 100.

  Resin coatings 17 and 18 are applied to the surface of the valve seat 122 of the valve case 100 and the surface of the annular projection 123. In detail, the resin coatings 17 and 18 are provided on the surface of the valve seat member 12 on the valve seat 122 side including the valve seat 122 and the surface on the annular projection 123 side including the annular protrusion 123. The material, the bending elastic modulus and the film thickness of the resin coatings 17 and 18 are the same as those described in the first embodiment.

  The relief valve 10 of the second embodiment described above reduces the number of parts and simplifies the configuration by integrally forming the valve case body 11 and the valve seat member 12 described in the first embodiment. Can. In addition, the relief valve 10 of the second embodiment can exhibit the same effects as those of the first embodiment.

Third Embodiment
A third embodiment will be described. The third embodiment is the same as the second embodiment except that the configuration of the resin coating is changed with respect to the second embodiment, and therefore, only the parts different from the second embodiment will be described.

  As shown in FIGS. 8 and 9, in the third embodiment, the resin coatings 18 and 19 are provided on the surface of the valve body 13 and the surface of the annular projection 123 of the valve case 100. In detail, the resin coatings 18 and 19 are provided on the entire surface of the valve body 13 and on the entire surface of the bottom of the mounting hole 22 including the annular protrusion 123 in the valve case 100. In the third embodiment, the resin coating is not provided on the surface of the valve seat 122. That is, the resin coating may be provided on one of the surface of the valve body 13 and the surface of the valve seat 122. The material, the flexural modulus and the film thickness of the resin coatings 18, 19 are the same as those described in the first embodiment.

  The third embodiment described above can also achieve the same effects as the first and second embodiments described above. In the third embodiment, for example, when it is difficult to apply a resin coating to the valve seat 122 formed in the deep portion of the flow path 111 of the valve case 100, the resin coating on the surface of the valve seat 122 may be omitted. It is possible. Also in the third embodiment, as in the first embodiment, the valve case 100 may be configured such that the valve case main body 11 and the valve seat member 12 are separate members.

Fourth Embodiment
A fourth embodiment will be described. In the fourth embodiment, a part of the configuration of the relief valve 10 and a part of the configuration of the resin coating are modified with respect to the first embodiment, and the other parts are the same as the first embodiment. Only parts different from the one embodiment will be described.

As shown in FIGS. 10 and 11, in the fourth embodiment, an annular washer member 31 is provided between the bottom surface 221 of the mounting hole 22 of the housing 21 of the compressor 2 and the valve seat member 12. There is. The washer member 31 is formed of, for example, a metal such as copper. The washer member 31 is in close contact with the bottom surface 221 of the mounting hole 22 and the valve seat member 12 by an axial force that clamps the male screw 112 of the valve case body 11 to the female screw 24 of the mounting hole 22 of the housing 21. Thereby, the washer member 31 functions as a seal member. Therefore, the washer member 31 prevents the CO ₂ refrigerant from leaking between the bottom surface 221 of the mounting hole 22 and the valve seat member 12.

  In the fourth embodiment, the resin coating 17 is provided on the surface of the valve seat 122 of the valve seat member 12. In detail, the resin coating 17 is provided on the entire surface of the valve seat member 12 on the valve seat 122 side. In the fourth embodiment, the resin coating is not provided on the surface of the valve seat member 12 on the bottom surface 221 side of the mounting hole 22. The material, the bending elastic modulus and the film thickness of the resin coating 17 are the same as those described in the first embodiment.

  The relief valve 10 according to the fourth embodiment described above provides the washer member 31 between the bottom surface 221 of the mounting hole 22 and the valve seat member 12 to form the annular protrusion 123 described in the first to third embodiments. And it is possible to abolish the resin coating applied there. Therefore, in the fourth embodiment, the process for applying the resin coating 17 to the valve seat member 12 can be simplified. In addition, the relief valve 10 of the fourth embodiment can also achieve the same effects as those of the first to third embodiments.

Fifth Embodiment
A fifth embodiment will be described. The fifth embodiment is provided with a gasket 32 in place of the washer member 31 described in the fourth embodiment, and the other parts are the same as the fourth embodiment, so only the parts different from the fourth embodiment are included. explain.

As shown in FIGS. 12 and 13, in the fifth embodiment, a plate-like gasket 32 is provided between the bottom surface 221 of the mounting hole 22 of the housing 21 of the compressor 2 and the valve seat member 12. There is. The gasket 32 is formed of, for example, a metal plate or a metal plate coated with a resin. The gasket 32 is in close contact with the bottom surface 221 of the mounting hole 22 and the valve seat member 12 by an axial force that clamps the male screw 112 of the valve case body 11 to the female screw 24 of the mounting hole 22 of the housing 21. Thereby, the gasket 32 functions as a seal member. Therefore, the gasket 32 prevents the CO ₂ refrigerant from leaking between the bottom surface 221 of the mounting hole 22 and the valve seat member 12.

  The relief valve 10 of the fifth embodiment described above arranges the gasket 32 between the bottom surface 221 of the mounting hole 22 and the valve seat member 12 so that the annular protrusion 123 described in the first to third embodiments described above. And it is possible to abolish the resin coating applied there. The relief valve 10 of the fifth embodiment can also provide the same effects as those of the first to fourth embodiments described above.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and appropriate modifications can be made within the scope of the claims. Moreover, said each embodiment is not mutually irrelevant and can be combined suitably, unless the combination is clearly impossible. Further, in each of the above-described embodiments, it is needless to say that the elements constituting the embodiment are not necessarily essential except when clearly indicated as being essential and when it is considered to be obviously essential in principle. Yes. Further, in the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of constituent elements of the embodiment are mentioned, it is clearly indicated that they are particularly essential and clearly limited to a specific number in principle. It is not limited to the specific number except when it is done. Further, in the above embodiments, when referring to the shape, positional relationship, etc. of the component etc., unless otherwise specified or in principle when limited to a specific shape, positional relationship, etc., the shape, etc. It is not limited to the positional relationship and the like.

(1) In the above embodiments, the relief valve 10 is described as being provided in the refrigeration cycle 1 using a CO ₂ refrigerant, but the invention is not limited thereto. The relief valve 10 may be provided in the refrigeration cycle 1 using a fluorocarbon-based refrigerant such as HFC-134a or HFO-1234yf.

  (2) Although the relief valve 10 is described as being attached to the housing 21 of the compressor 2 in each of the above embodiments, the present invention is not limited to this. The relief valve 10 may be attached to a component disposed between the discharge side of the compressor 2 and the suction side of the expansion valve 4 as a component on the high pressure side of the refrigeration cycle 1.

  (3) In each of the above embodiments, the compressor 2 constituting the refrigeration cycle 1 is described as being driven by power transmitted from the engine 7 of the vehicle via the belt 8 or the like, but the invention is not limited thereto. The compressor 2 may be driven by, for example, an electric motor.

  (4) In each said embodiment, although the valve body 13 was demonstrated as a spherical valve, it does not restrict to this. The shape of the valve body 13 can adopt various shapes, such as a conical shape, a plate shape, and a needle shape, for example.

  (5) In the above embodiments, the valve case 100, the valve case main body 11, the valve seat member 12 and the like included in the relief valve 10 are described as being formed of a metal material, but the invention is not limited thereto. Each configuration of the relief valve 10 may be formed of a hard material such as ceramic.

  (6) In each of the above-described embodiments, the relief valve 10 is described as being applied to the refrigeration cycle 1 constituting the vehicle air conditioner, but the invention is not limited thereto. The relief valve 10 may be applied to a refrigeration cycle that constitutes, for example, an air conditioner for a building or a water heater.

(Summary)
According to the first aspect of the present invention described in part or all of the above-described embodiments, the relief valve has a function of releasing the refrigerant from the refrigeration cycle when the refrigerant pressure in the refrigeration cycle becomes an abnormally high pressure. The relief valve comprises a valve case, a valve body, a biasing member and a resin coating. The valve case is attached to a mounting hole provided in a component on the high pressure side of the refrigeration cycle, and has a flow path for flowing the refrigerant and a valve seat provided in the middle of the flow path. The valve case is made of metal. The valve body is accommodated in the flow path of the valve case, and is provided so as to be able to be seated and separated from the valve seat. The biasing member biases the valve body toward the valve seat with a predetermined biasing force. The resin coating is formed of a resin having a commonly used heat resistant temperature higher than the temperature of the high pressure refrigerant of the refrigeration cycle, and is provided on at least one of the surface of the valve seat or the surface of the valve body.

According to the second aspect, the valve case further includes an annular protrusion that protrudes annularly toward the bottom surface of the mounting hole and is provided to surround the opening of the flow passage of the valve case. The resin coating is also provided on the surface of the annular protrusion. By using a resin for the coating applied to the surface of the annular protrusion, for example, even when a low molecular weight CO ₂ refrigerant is used, it is possible to prevent the CO ₂ refrigerant from permeating the resin coating. In addition, by using a resin having a commonly used heat-resistant temperature higher than the temperature of the high-pressure refrigerant in the refrigeration cycle for the coating, for example, even when using a CO ₂ refrigerant having a high operating pressure, it is possible to prevent thermal degradation of the resin coating. It is. Therefore, this relief valve can maintain the hermeticity of the refrigerant over long-term use.

  According to the third aspect, the valve case includes a valve case main body and a valve seat member. The valve case main body is fixed to a mounting hole provided in a component on the high pressure side of the refrigeration cycle, and has a flow path for flowing the refrigerant. The valve seat member is fixed to the valve case main body and has a flow path for flowing the refrigerant and a valve seat provided in the middle of the flow path. The valve case body and the valve seat member are formed of the same kind of metal. According to this, the linear expansion coefficients of the valve case main body and the valve seat member become the same. Therefore, even when both the valve case main body and the valve seat member are used in a high temperature and high pressure environment, it is possible to suppress minute deformation or distortion of the valve seat. If the valve case main body and the valve seat member are formed of resin, the valve case main body and the valve seat member creep and deform when used for a long time in a high temperature and high pressure environment, and the valve opening pressure changes or Sealing deterioration may occur. On the other hand, the valve case main body and the valve seat member are formed of metal, and the resin coating is applied thereto, so that the valve opening pressure of the valve body due to the creep deformation of the resin even when used for a long time under high temperature and high pressure environment Change and sealing can be prevented.

  According to a fourth aspect, the annular projection is provided on the valve seat member. The resin coating is provided on the surface of the valve seat of the valve seat member and the surface of the annular projection of the valve seat member without being provided on the valve body. According to this, since both the valve seat and the annular projection are provided on the valve seat member, it is possible to simplify the process of applying the resin coating. In addition, by applying a thin resin coating to the surface of the annular projection of the metal valve seat member, the set positions of the bottom surface of the mounting hole, the valve seat member and the valve case main body can be used for long-term use. It is possible to keep constant. Therefore, the biasing force by the biasing member is kept constant. Therefore, this relief valve can maintain the valve opening pressure of the valve body constant over long-term use.

  According to a fifth aspect, the resin coating has a flexural modulus of 3500 to 5000 MPa. According to this, by setting the bending elastic modulus of the resin coating to 3500 MPa or more, the breaking strength of the resin coating with respect to the biasing force of the biasing member becomes greater than the allowable strength, and the setting positions of the valve seat and the valve body Be kept constant. Therefore, since the biasing force by the biasing member is maintained constant over a long period of use, the relief valve can maintain the valve opening pressure of the valve disc constant. Further, by setting the bending elastic modulus of the resin coating to 5000 MPa or less, the resin coating is slightly deformed by the biasing force of the biasing member to such an extent that the valve opening pressure of the valve body is not affected. It is possible to prevent a gap from occurring. Therefore, this relief valve can maintain the hermeticity of the refrigerant over long-term use.

  According to a sixth aspect, the resin coating has a thickness of 20 to 120 μm. According to this, by setting the film thickness of the resin coating to 20 μm or more, the resin coating is slightly deformed by the biasing force of the biasing member to such an extent that the valve opening pressure of the valve body is not affected. It is possible to prevent a gap from occurring between the Therefore, this relief valve can maintain the hermeticity of the refrigerant over long-term use. Further, by setting the film thickness of the resin coating to 120 μm or less, even if the resin coating is creep-deformed temporarily due to the high load of the high pressure refrigerant and the biasing member, the change in the setting position of the valve seat and the valve body is extremely small. It becomes a thing. Therefore, the change of the biasing force of the biasing member becomes less than the allowable value. Therefore, this relief valve can maintain the valve opening pressure of the valve body constant over long-term use.

According to the seventh aspect, the refrigerant circulating in the refrigeration cycle is carbon dioxide. According to this, the operating pressure of the refrigeration cycle using the CO ₂ refrigerant is 4 to 7 times the operating pressure of the refrigeration cycle using the fluorocarbon refrigerant such as HFC-134a, and at the same time the refrigerant temperature on the high pressure side Becomes higher. Therefore, a relief valve applied to a refrigeration cycle using a CO ₂ refrigerant is required to open at a pressure 1.2 times or more the maximum working pressure of the refrigerant and to be required to be reproduced several times. Furthermore, the relief valve is required to close reliably during operation of the refrigeration cycle and to have high sealing performance. To meet such requirements, this relief valve applies a resin coating to the surface of the metal valve seat or the surface of the valve disc, so that the valve disc opening pressure and the refrigerant sealing property can be used over a long period of use. Can be maintained.

  According to an eighth aspect, the refrigeration cycle is a supercritical refrigeration cycle that uses carbon dioxide as a refrigerant at a pressure above the critical point. According to this, even when the relief valve is applied to a supercritical refrigeration cycle in which the working pressure of the refrigerant is high, it is possible to maintain the valve opening pressure of the valve and the sealing performance of the refrigerant over long-term use.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 10 Relief valve 11 Valve case main body 12 Valve seat member 13 Valve body 14 Spring 17, 18, 19 Resin coating 22 Mounting hole 100 Valve case 122 Valve seat

Claims (8)

In the relief valve that releases the refrigerant from the refrigeration cycle when the refrigerant pressure of the refrigeration cycle (1) becomes abnormally high pressure,
The flow path (111, 121) for flowing the refrigerant, and the valve seat (122) provided in the middle of the flow path, attached to the mounting hole (22) provided in the high-pressure component of the refrigeration cycle With metal valve cases (11, 12, 100),
A valve body (13) accommodated in the flow passage of the valve case and provided so as to be able to be seated on or away from the valve seat;
An urging member (14) for urging the valve body toward the valve seat with a predetermined urging force;
A relief valve comprising a resin coating (17, 19) formed of a resin having a commonly used heat resistant temperature higher than the temperature of the high pressure refrigerant of the refrigeration cycle and provided on the surface of the valve seat or the surface of the valve body . The valve case further has an annular protrusion (123) projecting annularly toward the bottom surface (221) of the mounting hole and provided to surround the opening of the flow passage of the valve case,
The relief valve according to claim 1, wherein the resin coating (18) is also provided on the surface of the annular protrusion. The valve case is
A valve case body (11) fixed to a mounting hole (22) provided in a component on the high pressure side of the refrigeration cycle and having a flow path (111) for flowing a refrigerant;
And a valve seat member (12) fixed to the valve case main body and having a flow path (121) for flowing the refrigerant, and the valve seat (122) provided in the middle of the flow path.
The relief valve according to claim 1, wherein the valve case body and the valve seat member are formed of the same kind of metal. The annular projection is provided on the valve seat member,
The relief valve according to claim 3, wherein the resin coating (17, 18) is provided on the surface of the valve seat of the valve seat member and the surface of the annular projection of the valve seat member.   The relief valve according to any one of claims 1 to 4, wherein the resin coating has a flexural modulus of 3500 to 5000 MPa.   The relief valve according to any one of claims 1 to 5, wherein the resin coating has a thickness of 20 to 120 m.   The relief valve according to any one of claims 1 to 6, wherein the refrigerant circulating in the refrigeration cycle is carbon dioxide.   The relief valve according to any one of claims 1 to 7, wherein the refrigeration cycle is a supercritical refrigeration cycle that uses carbon dioxide as a refrigerant at a pressure above a critical point.

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