Expansion valve

Abstract

To provide an expansion valve that allows compactification and weight reduction while suppressing an increase in manufacturing costs.SOLUTION: An expansion valve 1 has a valve body 2 with a valve chamber VC, a valve seat 20 and a refrigerant flow passage 23, a valve element 3 arranged in the valve chamber VC, a power element 8 that generates valve-opening force for separating the valve element 3 from the valve seat 20 to open a valve, and an operation rod 5 with one end abutting against the valve element 3. The power element 8 has a housing, a diaphragm 83 that divides the inside of the housing into a communication space that communicates with a pressure operation chamber PO and the refrigerant flow passage 23, and a stopper member 84 made of synthetic resin that abuts against the diaphragm 83 within the communication space. At least a portion of the valve body 2 that contacts the power element 8 is made of the synthetic resin. The stopper member 84 abuts against the other end of the operation rod 5 and is capable of transmitting the valve-opening force to the operation rod 5. In the state where the valve element 3 is seated on the valve seat 20, a valve chamber side end of the stopper member 84 protrudes into the refrigerant flow passage 23 from the inner periphery of the refrigerant flow passage 23.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an expansion valve. [Background technology]

[0002] Conventionally, for example, in refrigeration cycles used in air conditioners mounted on automobiles, a temperature-sensing type thermal expansion valve that adjusts the amount of refrigerant passing through depending on the temperature is used. Such a thermal expansion valve employs a power element that drives a valve body by the pressure of the enclosed working gas.

[0003] Here, the stopper member disposed in the power element has a function of transferring heat between the refrigerant passing through the expansion valve and the working gas, and a function of driving the working rod by being displaced in response to deformation of the diaphragm caused by the temperature expansion of the working gas. Regarding the function of transferring heat, it is necessary to appropriately set the responsiveness of the working gas to the temperature change of the refrigerant passing through the expansion valve, and if the responsiveness is too poor (i.e., if it is too sluggish), the time constant of the expansion valve becomes too large, which is undesirable for controlling the amount of refrigerant.

[0004] On the other hand, if the responsiveness is excessively good (i.e., excessively sensitive), the time constant of the expansion valve becomes too small, which may lead to the so-called hunting phenomenon in which the valve body frequently opens and closes in response to changes in the refrigerant temperature.

[0005] Factors that determine the time constant of the expansion valve include the size and thermal conductivity of the stopper member.

[0006] In recent years, energy saving in automobiles has been promoted, and there is a demand for smaller and lighter components in vehicle air conditioners. One idea for meeting such a demand is to make the power element smaller. By making the power element smaller, the weight of the power element can also be reduced. However, by making the power element smaller, the time constant of the expansion valve becomes smaller, and hunting becomes more likely to occur.

[0007] In response to this, Patent Document 1 discloses a power element in which the stopper member is made of a resin material and a metal material. By using such a stopper member, it is possible to suppress the heat transmitted to the diaphragm via the stopper member, so that the occurrence of hunting can be suppressed even if the power element is made compact. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-17961 Summary of the Invention [Problem to be solved by the invention]

[0009] However, when the stopper member is made of a resin material and a metal material as disclosed in Patent Document 1, there is a problem in that the manufacturing cost increases.

[0010] Therefore, an object of the present invention is to provide an expansion valve that can be made smaller and lighter while suppressing increases in manufacturing costs. [Means for solving the problem]

[0011] In order to achieve the above object, the expansion valve according to the present invention comprises: a valve body including a valve chamber, a valve seat, and a refrigerant flow path; a valve body disposed in the valve chamber; a power element provided in the valve body and generating a valve opening force that separates the valve body from the valve seat to open the valve; An actuating rod provided in the valve body and having one end in contact with the valve element, The power element includes a housing, a diaphragm that divides the inside of the housing into a pressure actuated chamber and a communication space that communicates with the refrigerant flow path, and a stopper member made of a synthetic resin that abuts against the diaphragm in the communication space, The stopper member is capable of transmitting the valve opening force to the actuating rod by contacting the other end of the actuating rod, The valve chamber side end of the stopper member protrudes into the refrigerant flow path from an inner periphery of the refrigerant flow path when the valve body is seated on the valve seat. Effect of the Invention

[0012] According to the present invention, it is possible to provide an expansion valve that can be made smaller and lighter while suppressing increases in manufacturing costs. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example in which the expansion valve according to the first embodiment is applied to a refrigerant circulation system, and shows the expansion valve in an open state. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing the expansion valve in the first embodiment, in a closed state. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing the periphery of the power element in the first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an expansion valve according to a second embodiment, and shows the valve in an open state. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing an expansion valve according to the second embodiment, in a closed state. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing the periphery of a power element in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] (Direction definition) In this specification, the direction from the valve disc 3 to the actuating rod 5 is defined as the "upward direction", and the direction from the actuating rod 5 to the valve disc 3 is defined as the "downward direction". Therefore, in this specification, the direction from the valve disc 3 to the actuating rod 5 is called the "upward direction" regardless of the position of the expansion valve 1. Furthermore, "cylinder" includes hollow cylinders and solid cylinders, and "synthetic resin" includes both thermoplastic resin and thermosetting resin, but it is preferable to use thermoplastic resin when performing thermal crimping, which will be described later.

[0016] (First embodiment) An overview of an expansion valve 1 including a power element in a first embodiment will be described with reference to Figs. 1 and 2. Fig. 1 is a schematic cross-sectional view showing an example in which the expansion valve 1 in this embodiment is applied to a refrigerant circulation system 100. Fig. 1 shows the expansion valve 1 in a maximum open state among communication states described later. Fig. 2 is a schematic cross-sectional view showing the expansion valve 1 in a non-communication state described later. Fig. 3 is an enlarged cross-sectional view showing the periphery of the power element in the first embodiment, in a communication state. In this embodiment, the expansion valve 1 is fluidly connected to a compressor 101, a condenser 102, and an evaporator 103. The center line of the operating rod 5 of the expansion valve 1 is taken as an axis L.

[0017] In FIGS. 1 and 2, an expansion valve 1 includes a valve body 2 having a valve chamber VC, a valve element 3, a biasing device 4, an actuating rod 5, and a power element 8.

[0018] At least a portion of the valve body 2 that contacts the power element is made of a synthetic resin material. In the present embodiment, as an example, the entire valve body 2 is made of a synthetic resin material. In addition to the valve chest VC, the valve body 2 includes a first flow path 21, a second flow path 22, an intermediate chamber 221, and a return flow path (also referred to as a refrigerant flow path) 23.

[0019] It is preferable that the inner diameter of the return flow passage 23 is uniform. The first flow passage 21 is a supply-side flow passage, and the refrigerant is supplied to the valve chamber VC via the supply-side flow passage. The second flow passage 22 is a discharge-side flow passage, and the fluid in the valve chamber VC is discharged to the outside of the expansion valve via the flow hole 27, the intermediate chamber 221, and the discharge-side flow passage.

[0020] The first flow passage 21 and the valve chamber VC communicate with each other through a connection passage 21a having a smaller diameter than the first flow passage 21. The valve chamber VC and the intermediate chamber 221 communicate with each other through the valve seat 20 and the flow hole 27.

[0021] The actuating rod insertion hole 28 formed above the intermediate chamber 221 has the function of guiding the actuating rod 5, and the annular recess 29 formed above the actuating rod insertion hole 28 has the function of accommodating the ring spring 6. The ring spring 6 has multiple spring pieces abutting against the outer periphery of the actuating rod 5 to apply a predetermined biasing force.

[0022] The valve disc 3 is disposed in the valve chamber VC. As shown in FIG. 2, when the valve disc 3 is seated on the valve seat 20 of the valve body 2, the flow of refrigerant through the flow hole 27 is restricted. This state is called a non-communicating state. However, even when the valve disc 3 is seated on the valve seat 20, a restricted amount of refrigerant may flow. On the other hand, when the valve disc 3 is separated from the valve seat 20, the flow of refrigerant passing through the flow hole 27 increases. This state is called a communicating state. The expansion valve 1 shown in FIG. 1 is in a maximum open state in which the valve disc 3 is fully open in the communicating state.

[0023] The actuating rod 5 is inserted with a predetermined gap through the flow hole 27. The lower end of the actuating rod 5 is in contact with the upper surface of the valve body 3. The upper end of the actuating rod 5 is fitted into a fitting hole 84c of a stopper member 84 described later.

[0024] The actuating rod 5 can press the valve element 3 in the valve opening direction against the biasing force of the biasing device 4. When the actuating rod 5 moves downward, the valve element 3 moves away from the valve seat 20, and the expansion valve 1 is in the open state.

[0025] 1 and 2, the biasing device 4 has a coil spring 41 formed by spirally winding a wire rod with a circular cross section, a valve body support 42, a spring receiving member 43, and a vibration-isolating member 44 sandwiched between the valve body support 42 and the coil spring 41. The spring receiving member 43 seals the valve chamber VC of the valve body 2, and has the function of supporting the end of the coil spring 41 that biases the valve body 3 toward the valve seat 20.

[0026] The spherical valve element 3 is welded to the upper surface of the valve element support 42, and the two are integrated together. The vibration-isolating member 44 has, for example, a radially protruding claw portion that elastically engages with the inner periphery of the valve chamber VC and has the function of suppressing vibration of the valve element 3. Note that the vibration-isolating member 44 is described in detail in, for example, JP 2018-025331 A, and therefore a detailed description thereof will be omitted.

[0027] Next, the power element 8 will be described. The power element 8 has an outer diameter of, for example, 30 mm or less, and includes a plug 81, an upper cover member 82, a diaphragm 83, a receiving member 86, and a stopper member 84. The upper cover member 82 and the receiving member 86 form a housing.

[0028] An opening 82a (FIG. 3) is formed at the top of the generally conical upper cover member 82, and can be sealed with a plug 81.

[0029] The diaphragm 83 is made of a thin metal (for example, SUS) plate material on which a plurality of concentric circular projections and recesses are formed, and has approximately the same outer diameter as the outer diameters of the upper cover member 82 and the receiving member 86.

[0030] 3, the receiving member 86 is formed, for example, by press molding a metal plate, and has an annular first flange portion 86a having an outer diameter substantially the same as that of the flange portion 82b of the top cover member 82, a short cylindrical portion 86b connected to the inner periphery of the first flange portion 86a, and a second flange portion 86c connected to the lower end of the short cylindrical portion 86b and extending radially inward. Note that it is preferable that the recess 2a of the valve body 2 has a stepped shape corresponding to the first flange portion 86a, the short cylindrical portion 86b, and the second flange portion 86c.

[0031] The stopper member 84 made of synthetic resin material includes a base 84a and a protruding portion 84b. At least a part of the upper surface of the base 84a abuts against the diaphragm 83. When the base 84a moves toward the valve chamber VC, it abuts against the receiving member 86 to stop the movement and prevent the diaphragm 83 from being further deformed. The base 84a constitutes the upper portion of the stopper member 84. The base 84a is formed, for example, in a disk shape. Hereinafter, the base 84a will be referred to as the disk portion 84a. The protruding portion 84b protrudes from the base 84a. The protruding portion 84b is formed in a columnar shape. The protruding portion 84b is formed, for example, in a cylindrical shape. That is, the disk portion 84a and the protruding portion 84b, which is, for example, cylindrical and has a smaller diameter than the disk portion 84a, are connected together. A blind hole-shaped fitting hole 84c is formed in the center of the lower end of the protruding portion 84b.

[0032] The opening of the fitting hole 84c and the region near the opening of the inner circumference of the fitting hole 84c have a gap between them and the operating rod 5. This gap increases the surface area of ​​the protruding portion 84b exposed in the return flow passage 23. In the present embodiment, as an example, the region near the opening of the inner circumference of the fitting hole 84c is formed into a conical surface.

[0033] It is preferable to form a tapered inclined surface portion 84d, for example, on the outer periphery of the lower end of the protruding portion 84b, the diameter of which decreases as it approaches the valve chamber VC. The inclined surface portion 84d may have an arc-shaped outer periphery cross section. The inclined surface portion 84d is disposed in the return flow passage 23 when the expansion valve 1 is in a non-communicating state and a communicating state. By providing the inclined surface portion 84d, the flow of the refrigerant in the return flow passage 23 can be made smooth even if the protruding portion 84b protrudes into the return flow passage 23. Furthermore, when the expansion valve 1 is in a non-communicating state, at least a part of the upper edge of the inclined surface portion 84d of the protruding portion 84b is disposed in the return flow passage 23. With this structure, when the expansion valve 1 is in a non-communicating state, at least a part of the part of the outer periphery of the protruding portion 84b other than the inclined surface portion 84d faces the opening edge of the communication hole 2b on the return flow passage 23 side. As a result, the gap between the opening of the communication hole 2b and the protruding portion 84b can be made smaller than when the opening edge of the communication hole 2b and the inclined surface portion 84d face each other. Therefore, even if a force is applied in a direction that tilts the stopper member 84 when the expansion valve 1 opens from a non-communicating state, the protruding portion 84b abuts against the opening edge of the communication hole 2b, so that the degree of tilt can be kept small.

[0034] Also, the stopper member 84 can be joined to the upper end of the operating rod 5 by insert molding or the like.

[0035] 2, in this embodiment, the dimension of the protruding portion 84b perpendicular to the axis of the protruding portion 84b is longer than the dimension of the protruding portion 84b along the axis, in other words, the dimension from the base 84a to the tip of the protruding portion 84b. As a result, the circumferential length of the protruding portion 84b can be increased, and the area of ​​the circumferential surface of the protruding portion 84b exposed in the return flow passage 23 can be increased while suppressing the amount of protrusion of the protruding portion 84b into the return flow passage 23.

[0036] The assembly procedure of the power element 8 will be described. The stopper member 84 is disposed between the diaphragm 83 and the receiving member 86, and in a state in which the protruding portion 84b protrudes outward through the inner periphery of the second flange portion 86c, the outer peripheries of the upper cover member 82, the diaphragm 83, and the receiving member 86 are overlapped, and the outer peripheries are circumferentially welded together by, for example, TIG welding, laser welding, plasma welding, or the like, to form an integrated unit.

[0037] Next, a working gas is injected into the space surrounded by the upper cover member 82 and the diaphragm 83 (called the pressure actuated chamber PO) through the opening 82a formed in the upper cover member 82, and then the opening 82a is sealed with a plug 81, and the plug 81 is fixed to the upper cover member 82 using projection welding or the like.

[0038] At this time, the diaphragm 83 is subjected to pressure by the working gas sealed in the pressure actuated chamber PO, causing it to protrude toward the receiving member 86, and is supported by abutting against the upper surface of the stopper member 84, which is located in the lower space (also called the communicating space) LS surrounded by the diaphragm 83 and the receiving member 86.

[0039] The process of assembling the power element 8 assembled as described above to the valve body 2 will now be described. Before assembly, as shown by the dotted line in Fig. 3, a thin-walled cylindrical crimped portion 2c is formed around the recess 2a at the upper end of the valve body 2 and protrudes upward. First, the actuating rod 5 is inserted into the valve body 2 from above through the communication hole 2b, and then the power element 8 is inserted into the crimped portion 2c and pressed against the valve body 2 from above. At this time, the upper end of the actuating rod 5 fits into the fitting hole 84c of the stopper member 84.

[0040] While maintaining the pressing state, heat is applied to the crimped portion 2c to deform the crimped portion 2c so that it falls inward in the radial direction over its entire circumference (shown by solid lines in FIG. 3), and the power element 8 is fixed to the valve body 2 in a state where the outer periphery of the housing is wrapped in the crimped portion 2c. Alternatively, heat may be applied to the crimped portion 2c without applying pressure to the crimped portion 2c to deform the crimped portion 2c so that it falls inward in the radial direction over its entire circumference. As a result, the outer periphery of the housing is held in the axial direction L between the valve body 2 and the crimped portion 2c extending from the valve body 2. As described above, in this embodiment, the fixing method of applying heat to the crimped portion 2c to deform it and fixing the power element by the deformed crimped portion 2c is thermal crimping. However, the method of fixing the power element 8 to the valve body 2 is not limited to thermal crimping, and may be, for example, adhesion using an adhesive.

[0041] At this time, a packing PK is interposed between the lower surface of the receiving member 86 of the power element 8 and the bottom surface of the recess 2a of the valve body 2 to prevent leakage of the refrigerant from the recess 2a when the power element 8 is attached to the valve body 2. In this state, the lower space LS of the power element 8 communicates with the return flow path 23, i.e., they have the same internal pressure.

[0042] In addition, when the power element 8 is fixed to the valve body 2, the lower end (valve chamber side end) of the protruding portion 84b of the stopper member 84 protrudes from the inner circumference of the return flow passage 23 into the return flow passage 23 in both the communicating state and the non-communicating state. The stopper member 84, for example, protrudes from the inner circumference of the return flow passage 23 toward the center of the return flow passage 23. More specifically, as shown in FIG. 3, when the lower surface of the disk portion 84a of the stopper member 84 abuts against the upper surface of the second flange portion 86c of the receiving member 86 (when the valve is open), the lower end of the protruding portion 84b protrudes from the inner circumference of the return flow passage 23 by a protruding amount a. Note that, when the lower surface of the disk portion 84a of the stopper member 84 is separated from the upper surface of the second flange portion 86c of the receiving member 86 when the valve is closed, the lower end of the protruding portion 84b protrudes from the inner circumference of the return flow passage 23 by a protruding amount (a-valve body stroke amount) smaller than the protruding amount a in FIG. 3. That is, the lower end of the protruding portion 84b protrudes from the inner periphery of the return flow passage 23 even when the valve is closed.

[0043] (Expansion valve operation) An operation example of the expansion valve 1 will be described with reference to Figures 1 and 2. The refrigerant pressurized by the compressor 101 is liquefied by the condenser 102 and sent to the expansion valve 1. The refrigerant adiabatically expanded by the expansion valve 1 is sent to the evaporator 103, where it is heat exchanged with the air flowing around the evaporator. The refrigerant returning from the evaporator 103 is returned to the compressor 101 side through the expansion valve 1 (more specifically, the return flow path 23). At this time, by passing through the evaporator 103, the fluid pressure in the second flow path 22 becomes greater than the fluid pressure in the return flow path 23.

[0044] A high-pressure refrigerant is supplied to the expansion valve 1 from a condenser 102. More specifically, the high-pressure refrigerant from the condenser 102 is supplied to the valve chest VC via a first flow path 21.

[0045] As shown in Fig. 2, when the valve disc 3 is seated on the valve seat 20 (in a non-communicating state), the flow rate of the refrigerant sent from the valve chamber VC through the flow hole 27, the intermediate chamber 221, and the second flow path 22 to the evaporator 103 is restricted. On the other hand, when the valve disc 3 is separated from the valve seat 20 (in a communicating state) as shown in Fig. 1, the flow rate of the refrigerant sent from the valve chamber VC through the flow hole 27, the intermediate chamber 221, and the second flow path 22 to the evaporator 103 increases. The expansion valve 1 is switched between a closed state and an open state by an actuating rod 5 connected to a power element 8 via a stopper member 84.

[0046] 1 and 2, a pressure actuated chamber PO and a lower space LS separated by a diaphragm 83 are provided inside the power element 8. The lower space LS communicates with the return flow path 23 via gaps between the protruding portion 84b of the stopper member 84 and the communication hole 2b and the second flange portion 86c of the receiving member 86, allowing the refrigerant to enter.

[0047] Here, when the working gas in the pressure actuated chamber PO is liquefied, the diaphragm 83 rises, causing the stopper member 84 and the actuating rod 5 to move upward in response to the biasing force of the coil spring 41, and the valve body 3 seats on the valve seat 20 (Figure 2).

[0048] On the other hand, when the liquefied working gas vaporizes, the diaphragm 83 is pressed downward to generate a valve-opening force, and the stopper member 84 transmits the valve-opening force to the actuating rod 5, which moves downward and separates the valve body 3 from the valve seat 20 (FIG. 1). In this way, the expansion valve 1 is switched between the open and closed states.

[0049] Therefore, the volume of the working gas in the pressure actuated chamber PO changes depending on the temperature and pressure of the refrigerant flowing through the return flow path 23, thereby driving the actuating rod 5. In other words, in the expansion valve 1 shown in Fig. 1 and Fig. 2, the amount of refrigerant supplied from the expansion valve 1 to the evaporator 103 is automatically adjusted depending on the temperature and pressure of the refrigerant returning from the evaporator 103 to the expansion valve 1.

[0050] Here, if the valve body 2 and the stopper member 84 of the power element 8 were made of metal, heat transfer between the return flow path 23 and the pressure actuated chamber PO would occur not only through the refrigerant moving from the return flow path 23 to the lower space LS, but also through the crimped portion 2c of the valve body 2 and the stopper member 84, which would reduce the time constant of the expansion valve 1 and could result in hunting, etc.

[0051] In contrast, in this embodiment, by making the stopper member 84 from a synthetic resin, in the expansion valve 1 whose time constant tends to become smaller as the power element 8 is made smaller, heat transfer to the diaphragm 83 via the stopper member 84 is suppressed, thereby making it possible to suppress hunting and the like. However, according to the results of studies by the present inventors, it was found that if the stopper member 84 is made from a synthetic resin, the time constant becomes too large, which may hinder proper operation of the expansion valve.

[0052] Therefore, in this embodiment, the lower end of the protruding portion 84b of the stopper member 84 protrudes radially inward from the inner circumference of the return passage 23 in both the communicating and non-communicating states. Therefore, the refrigerant flowing through the return passage 23 changes direction when it hits the outer circumference of the protruding portion 84b, and easily enters the lower space LS through the gaps between the protruding portion 84b and the communication hole 2b and the second flange portion 86c. This makes it possible to prevent the time constant from becoming too large, and to achieve appropriate operation of the expansion valve 1 while suppressing hunting and the like.

[0053] In addition to the above effects, by having the protruding portion 84b of the stopper member 84 protrude into the return flow path 23, the surface area of ​​the stopper member 84 that comes into contact with the refrigerant flowing in the return flow path 23 is increased, making it easier for the temperature of the stopper member 84 to approach the temperature of the refrigerant flowing in the return flow path 23, thereby preventing the time constant from becoming larger.

[0054] Furthermore, as a structure for fixing the power element 8 to the valve body 2, the power element 8 is fixed to the valve body 2 by wrapping the outer periphery of the housing of the power element 8 with a part of the valve body 2. In other words, since a structure is not adopted in which a male thread is formed on the power element 8, a female thread is formed on the valve body 2, and the power element 8 is fixed to the valve body 2 by screwing these male and female threads together, there is no need to form male and female threads, and accordingly it is possible to make the power element 8 and the valve body 2 smaller in size.

[0055] Furthermore, since crimping is used as the fixing structure, the power element 8 can be fixed to the valve body 2 with a relatively simple structure.

[0056] Furthermore, by making at least the portion of the valve body 2 that comes into contact with the power element 8 from a synthetic resin, the weight of the valve body 2 can be reduced.

[0057] Furthermore, by making the entire valve body 2 from a synthetic resin, it is possible to reduce the weight of the valve body 2.

[0058] Furthermore, the inclined surface portion 84d of the protruding portion 84b of the stopper member 84 is formed in a portion that protrudes into the return flow passage 23 in both the communicating state and the non-communicating state of the expansion valve.

[0059] In the above embodiments, the entire valve body is formed from synthetic resin, but for example, the lower half on the valve chamber VC side may be made of metal, and the upper half to which the power element 8 is attached (at least the portion in contact with the power element 8) may be made of synthetic resin, and the valve body may be formed by joining these together.

[0060] Second Embodiment Fig. 4 and Fig. 5 are schematic cross-sectional views showing an expansion valve 1A in a second embodiment. Fig. 4 shows the expansion valve 1A in a communicating state in a maximum open state, but the refrigeration cycle is omitted. Fig. 5 shows the expansion valve 1A in a non-communicating state. Fig. 6 is an enlarged cross-sectional view showing the periphery of a power element in the second embodiment.

[0061] In this embodiment, only the configurations of the valve body 2A and the stopper member 84A are different from those of the first embodiment, and the other configurations, including the refrigeration cycle, are the same as those of the first embodiment, so that a duplicated description will be omitted.

[0062] The valve body 2A differs from the first embodiment only in the inner peripheral shape of the return flow passage 23A. More specifically, a tapered surface 23Aa (the inner peripheral surface of the flow passage recess recessed toward the power element side) that narrows toward the power element 8 side is formed on the inner peripheral surface of the return flow passage 23A, and the upper end of the tapered surface 23Aa is connected to the inner peripheral surface of the communication hole 2b. That is, the tapered surface 23Aa constitutes a part of the inner peripheral surface of the return flow passage 23A. The refrigerant flowing through the return flow passage 23A smoothly passes through the tapered surface 23Aa, so that the pressure loss is not significantly increased compared to the first embodiment. The flow passage recess is not limited to a tapered surface.

[0063] The tapered surface 23Aa may be formed by cutting after the inner circumference of the return flow passage 23A of the valve body 2A is molded by a die, or may be formed at the same time as molding using a slide die or the like, and is not limited to the method of formation. The other configurations are the same as those of the first embodiment, so repeated explanations will be omitted.

[0064] The stopper member 84A has a shorter axial length of a protrusion 84Ab than that of the first embodiment. The rest of the configuration is the same as that of the first embodiment, so a duplicated description will be omitted.

[0065] As shown in FIG. 6, when the power element 8 is fixed to the valve body 2A, the lower end of the protrusion 84Ab of the stopper member 84A, which is located radially inward of the tapered surface 23Aa, protrudes radially inward from the inner circumference of the return flow path 23A in both the connected and non-connected states.

[0066] More specifically, as shown in FIG. 6, in a state where the lower surface of the disk portion 84a of the stopper member 84A is in contact with the upper surface of the second flange portion 86c of the receiving member 86 (when the valve is opened), the distance from the upper end of the tapered surface 23Aa to the lower end of the protruding portion 84Ab is the protruding amount b, and the distance from the inner periphery of the return flow path 23 other than the tapered surface 23Aa to the lower end of the protruding portion 84Ab is the protruding amount c. At this time, it is preferable that b is equal to or approximately equal to a, and 0 < c < a. However, the protruding amount b may be a positive value and the protruding amount c may be a negative value (the lower end of the protruding portion 84Ab is on the valve chamber VC side from the upper end of the tapered surface 23Aa and on the power element 8 side from the lower end of the tapered surface 23Aa). When the valve is closed, even when the lower surface of the disk portion 84a of the stopper member 84A is separated from the upper surface of the second flange portion 86c of the receiving member 86, the lower end of the protruding portion 84b protrudes from the inner periphery of the return flow path 23 by a protruding amount (b - valve body stroke amount) smaller than the protruding amount b in FIG. 6. That is, even when the valve is closed, the lower end of the protruding portion 84Ab protrudes from the inner periphery of the return flow path 23.

[0067] According to the present embodiment, by forming the tapered surface 23Aa in the return flow path 23A, compared with the first embodiment, even though the length of the protruding portion 84Ab of the stopper member 84A is short, the length of the refrigerant immersed in the refrigerant passing through the return flow path 23A hardly changes. Therefore, even though the cost of the stopper member 84A can be reduced and weight reduction can be achieved, an appropriate time constant of the expansion valve 1A can be ensured.

[0068] In the present embodiment, the tapered surface 23Aa is formed as a conical surface as an example. However, the tapered surface 23Aa is not limited to a conical surface. In other examples, the tapered surface 23Aa may be a tapered surface formed in a planar shape that has a predetermined width in a direction orthogonal to the direction in which the refrigerant flows (in other words, a direction orthogonal to the axis of the return flow path 23) and is inclined toward the power element. Note that the present invention is not limited to the above-described embodiments. Within the scope of the present invention, any component of the above-described embodiments can be modified. Also, addition or omission of any component in the above-described embodiments is possible.

[0069] This specification includes the disclosure of the following inventions. (First aspect) a valve body including a valve chamber, a valve seat, and a refrigerant flow path; a valve body disposed in the valve chamber; a power element provided in the valve body and generating a valve opening force that separates the valve body from the valve seat to open the valve; An actuating rod provided in the valve body and having one end in contact with the valve element, The power element includes a housing, a diaphragm that divides the inside of the housing into a pressure actuated chamber and a communication space that communicates with the refrigerant flow path, and a stopper member made of a synthetic resin that abuts against the diaphragm in the communication space, The stopper member is capable of transmitting the valve opening force to the actuating rod by contacting the other end of the actuating rod, When the valve body is seated on the valve seat, a valve chamber side end of the stopper member protrudes into the refrigerant flow path from an inner periphery of the refrigerant flow path. An expansion valve characterized by:

[0070] (Second aspect) a flow passage recess that is recessed toward the power element side is formed on an inner circumference of the refrigerant flow passage around the valve chamber side end of the stopper member; An expansion valve according to a first aspect, characterized in that:

[0071] (Third aspect) The flow path recess has a tapered surface facing the power element. An expansion valve according to a second aspect,

[0072] (Fourth aspect) The outer periphery of the power element housing is surrounded by a portion of the valve body. The expansion valve according to any one of the first to third aspects, characterized in that:

[0073] (Fifth aspect) The outer periphery of the housing of the power element is held and fixed between the valve body and a crimping portion extending from the valve body along the axial direction of the valve body. An expansion valve according to a fourth aspect,

[0074] (Sixth Form) the stopper member has a base portion in contact with the diaphragm and a protruding portion connected to the base portion, and a valve chamber side end portion of the protruding portion protrudes into the refrigerant flow path from an inner periphery of the refrigerant flow path. The expansion valve according to any one of the first to fifth aspects, characterized in that

[0075] At least a portion of the valve body that contacts the power element is made of synthetic resin. The expansion valve according to any one of the first to sixth aspects, [Explanation of symbols]

[0076] 1, 1A: Expansion valve 2, 2A: Valve body 3: Valve body 4: Actuating device 5: Operating rod 6: Ring spring 8: Power Element 20: Valve seat 21: First flow path 22: Second flow path 221: Intermediate Room 23, 23A: Return flow path 27: Ventilation hole 28: Actuating rod insertion hole 29: Annular recess 41: Coil spring 42: Valve body support 43: Spring support member 81: Stopper 82: Top cover member 83: Diaphragm 84, 84A: Stopper member 86: Support member 100: Refrigerant circulation system 101: Compressor 102: Capacitor 103: Evaporator VC: Valve chamber

Claims

1. a valve body including a valve chamber, a valve seat, and a refrigerant flow path; a valve body disposed in the valve chamber; a power element provided in the valve body and generating a valve opening force that separates the valve body from the valve seat to open the valve; An actuating rod provided in the valve body and having one end in contact with the valve element, The power element includes a housing, a diaphragm that divides the inside of the housing into a pressure actuated chamber and a communication space that communicates with the refrigerant flow path, and a stopper member made of a synthetic resin that abuts against the diaphragm in the communication space, The stopper member is capable of transmitting the valve opening force to the actuating rod by contacting the other end of the actuating rod, When the valve body is seated on the valve seat, a valve chamber side end of the stopper member protrudes into the refrigerant flow path from an inner periphery of the refrigerant flow path. An expansion valve characterized by:

2. a flow passage recess that is recessed toward the power element side is formed on an inner circumference of the refrigerant flow passage around the valve chamber side end of the stopper member; 2. The expansion valve according to claim 1 .

3. The flow path recess has a tapered surface facing the power element.

3. The expansion valve according to claim 2.

4. The outer periphery of the power element housing is surrounded by a portion of the valve body. The expansion valve according to any one of claims 1 to 3.

5. The outer periphery of the housing of the power element is held and fixed between the valve body and a crimping portion extending from the valve body along the axial direction of the valve body.

5. The expansion valve according to claim 4.

6. the stopper member has a base portion in contact with the diaphragm and a protruding portion connected to the base portion, and a valve chamber side end portion of the protruding portion protrudes into the refrigerant flow path from an inner periphery of the refrigerant flow path.

2. The expansion valve according to claim 1 .

7. At least a portion of the valve body that contacts the power element is made of synthetic resin.

2. The expansion valve according to claim 1 .

Images