Expansion valve

Abstract

To provide an expansion valve that ensures valve controllability with a small opening degree, has a positive flow, and can cancel influence of fluid pressure on opening / closing valve operation.SOLUTION: An expansion valve comprises: a valve body 3 having an accommodated part that is accommodated in an expansion chamber in a state of being seated on a valve seat 20; a biasing part that biases the valve body toward the valve seat; a power element 8 that is provided in a site of the valve body 2 that faces the valve seat with a pressure chamber interposed therebetween, and generates a driving force for moving the valve body in a direction away from the valve seat; a transmission part that is arranged along an axial line of the valve seat, and transmits the driving force of the power element to the accommodated part; a partition part that is provided integrally with the transmission part in a movable manner, and partitions the pressure chamber into a valve chamber on the valve seat side and a back pressure chamber on the power element side; and an introduction path that guides fluid having flowed into a second flow path to the back pressure chamber.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, in the refrigeration cycle used in large refrigeration and cooling devices, a temperature-sensing expansion valve that adjusts the amount of refrigerant passing through depending on the temperature is used. There are two types of expansion valves: internal pressure equalization type and external pressure equalization type, and they are used depending on the pressure loss inside the evaporator. That is, the internal pressure equalization type is used when the pressure loss inside the evaporator is constant or relatively small, and the external pressure equalization type is often used when the pressure loss is relatively large.

[0003] In addition, the valve chamber of the expansion valve is connected to a high-pressure flow path through which the high-pressure refrigerant pressurized by the compressor enters, and a low-pressure flow path through which the refrigerant flows out toward the evaporator, which causes a large pressure difference across the valve seat on which the valve disc sits. When the fluid flows in the direction that the valve disc moves away from the valve seat, it is called a forward flow, and when the fluid flows in the opposite direction, that is, in the direction that the valve disc moves toward the valve seat, it is called a reverse flow.

[0004] In expansion valves used with forward flow, a flange portion that protrudes radially outward beyond the orifice is provided on the valve body, and, for example, three actuating rods are arranged between the stopper member of the power element and the flange portion, and the displacement of the stopper member is often transmitted to the valve body via the actuating rods.

[0005] Here, the lengths of the three actuating rods, the shapes of the stopper member and the valve body, etc. vary due to manufacturing errors. For example, even if the variation in the length of the actuating rods is within the tolerance range, the axis of the valve body may be tilted relative to the axis of the expansion valve due to the difference in length. If the axis of the valve body is tilted, there is a risk of competition between the valve body or actuating rods and the valve body. Such competition has an adverse effect on the movement of the valve body, especially immediately after the valve is opened or immediately before the valve is closed, and may result in hunting, vibration of the valve body, etc.

[0006] In contrast, in the expansion valve described in Patent Document 1, the valve element is biased in the valve opening direction by the pressure of the refrigerant on the high-pressure flow path side due to the forward flow, and further, the valve element and the actuating rod are integrated while sharing a common axis, and are then connected to a stopper member. The expansion valve in Patent Document 1 has the potential to stabilize control of the valve element when the opening degree is small, compared to an expansion valve with multiple actuating rods. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-51347 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of a forward flow, the valve element of the expansion valve is biased in the valve opening direction, so in order to achieve highly accurate valve control, it is necessary to take into consideration the pressure difference between the high-pressure flow path and the low-pressure flow path. However, in the expansion valve of Patent Document 1, sufficient consideration is not given to the pressure difference.

[0009] The present invention has been made in consideration of the problems of the conventional technology, and aims to provide an expansion valve that ensures valve controllability at a small opening degree, has a positive flow, and can cancel the effects of fluid pressure on the opening and closing operation of the valve. [Means for solving the problem]

[0010] In order to achieve the above object, the expansion valve according to the present invention comprises: a valve body including a valve seat, a pressure chamber formed on a primary side of the valve seat, a first flow passage communicating with the pressure chamber and having one end opening to the outside, an expansion chamber formed on a secondary side of the valve seat, and a second flow passage communicating with the expansion chamber and having one end opening to the outside; a valve body that is seated on the valve seat in a direction from the expansion chamber to the pressure chamber and moves away from the pressure chamber in a direction from the pressure chamber to the expansion chamber, the valve body including an accommodated portion that is accommodated in the expansion chamber when seated on the valve seat; a biasing portion that biases the valve body toward the valve seat; a power element provided in a portion of the valve body facing the valve seat across the pressure chamber, the power element generating a driving force that moves the valve body in a direction away from the valve seat; a transmission portion disposed along an axis of the valve seat and configured to transmit a driving force of the power element to the accommodated portion; a partition part that is movably provided integrally with the transmission part and divides the pressure chamber into a valve chamber on the valve seat side and a back pressure chamber on the power element side; and an introduction passage that introduces the fluid that has flowed out into the second flow passage into the back pressure chamber. Effect of the Invention

[0011] The present invention makes it possible to provide an expansion valve that ensures valve controllability at a small opening degree, has a positive flow, and can cancel the effect of fluid pressure on the opening and closing operation of the valve. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a vertical cross-sectional view of an expansion valve according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view of the valve body and its vicinity in the configuration of FIG. [Diagram 3] FIG. 3 is an enlarged longitudinal sectional view showing the vicinity of a valve body of an expansion valve according to a second embodiment. [Figure 4] FIG. 4 is an enlarged view of the vicinity of the collar according to the second embodiment. [Diagram 5] FIG. 5 is an enlarged longitudinal sectional view showing the vicinity of a valve body of an expansion valve according to a third embodiment. [Figure 6] FIG. 6 is an enlarged longitudinal sectional view showing the vicinity of a valve body of an expansion valve according to a fourth embodiment. [Figure 7]FIG. 7 is an enlarged longitudinal sectional view showing the vicinity of the valve body of the expansion valve according to the fifth embodiment. [Figure 8] FIG. 8 is an enlarged longitudinal sectional view showing the vicinity of the valve body of the expansion valve according to the sixth embodiment. [Figure 9] FIG. 9 is an enlarged longitudinal sectional view showing the vicinity of the valve body of the expansion valve according to the seventh embodiment. [Figure 10] FIG. 10 is an enlarged longitudinal sectional view showing the vicinity of a valve body of an expansion valve according to an eighth embodiment. [Figure 11] FIG. 11 is an enlarged longitudinal sectional view showing the vicinity of a valve body of an expansion valve according to a ninth embodiment. [Figure 12] FIG. 12 is an enlarged longitudinal sectional view showing the vicinity of the valve body of the expansion valve according to the tenth embodiment. [Figure 13] FIG. 13 is an enlarged view of the seal pressing portion and its vicinity according to the tenth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification, regardless of the position of the expansion valve, the direction from the valve disc to the power element is defined as the "upward direction," and the direction from the power element to the valve disc is defined as the "downward direction."

[0014] (First embodiment) FIG. 1 is a vertical cross-sectional view of an external pressure equalizing expansion valve 1 according to a first embodiment.

[0015] 2, the expansion valve 1 mainly includes a valve body 2 having a valve chamber VC, a valve element 3, an urging device 4, an actuating rod 5, and a power element 8. The center line of the valve element 3 is defined as an axis L of the expansion valve 1. The actuating rod 5 has a common axis with the axis L, including in the embodiments described later.

[0016] The cylindrical valve body 2 has, from the upper end side, a first inner circumferential portion 21a, a second inner circumferential portion 21b having a larger diameter than the first inner circumferential portion 21a, a third inner circumferential portion 21c having a larger diameter than the second inner circumferential portion 21b and forming a valve chamber VC therein, a fourth inner circumferential portion 21d having a larger diameter than the third inner circumferential portion 21c, a fifth inner circumferential portion 21e having a smaller diameter than the fourth inner circumferential portion 21d, and a sixth inner circumferential portion 21f, which form a through hole 21 with a circular cross section that penetrates the valve body 2 from top to bottom. Including in the embodiment described later, the third inner circumferential portion 21c constitutes the valve chamber inner circumferential portion. In this embodiment, the second inner circumferential portion 21b constitutes the back pressure chamber inner circumferential portion.

[0017] The lower end side of the third inner circumferential portion 21c overlaps with the upper end side of the fourth inner circumferential portion 21d in the direction perpendicular to the axis L, and a cylindrical portion 21g is formed between the lower end side of the third inner circumferential portion 21c and the upper end side of the fourth inner circumferential portion 21d. The lower end of the third inner circumferential portion 21c constitutes the valve seat 20. With respect to the valve seat 20, the side of the first flow path 22 connected to the compressor side (not shown) is referred to as the primary side, and the side of the second flow path 23 connected to the evaporator side (not shown) is referred to as the secondary side.

[0018] Furthermore, the valve body 2 has a first flow passage (high-pressure side flow passage) 22 extending in a direction perpendicular to the axis L and connected to the third inner circumferential portion 21c, a second flow passage 23 extending in a direction perpendicular to the axis L and connected to the fourth inner circumferential portion 21d, and a pressure equalizing hole 24. In the through hole 21, a pressure chamber S1 is formed on the primary side of the valve seat 20, and an expansion chamber S2 is formed on the secondary side of the valve seat 20. The pressure chamber S1 includes a valve chamber VC. The first flow passage 22, which is a supply side flow passage communicating with the pressure chamber S1, has one end opening toward the outside and connected to the primary piping H1, and a high-pressure refrigerant is supplied to the valve chamber VC via the supply side flow passage. The second flow passage (low-pressure side flow passage) 23, which is a discharge side flow passage communicating with the expansion chamber S2, has one end opening toward the outside and connected to the secondary piping H2, and the refrigerant that flows from the valve chamber VC to the fourth inner circumferential portion 21d via the valve seat 20 is discharged to the outside of the expansion valve via the discharge side flow passage.

[0019] The pressure equalizing hole 24 has one end that opens toward the outside and is connected to a pressure equalizing pipe not shown, and extends, for example, parallel to the second flow path 23 and then extends, for example, parallel to the through hole 21 without communicating with the through hole 21, and the other end opens on the upper end side (lower space LC) of the valve body 2.

[0020] The valve body 3 is disposed in the through hole 21 and comprises a valve body base 30a made of metal (e.g., SUS) and a valve body tubular portion 30b made of metal (e.g., brass). As shown in Fig. 2, the valve body base 30a comprises, from the upper end side, a small diameter cylindrical portion 31, a small taper portion 32 which increases in diameter downward, a medium diameter cylindrical portion 33 which is larger in diameter than the small diameter cylindrical portion 31, a fitting cylindrical portion 34 which is larger in diameter than the medium diameter cylindrical portion 33, a large diameter cylindrical portion 35 which is larger in diameter than the fitting cylindrical portion 34, and a flange portion 36 which are coaxially connected to each other.

[0021] The valve body tubular portion 30b, which has a uniform inner diameter, is composed of, from the upper end side, a small diameter tubular portion 37, a large taper tubular portion 38 that is connected to the small diameter tubular portion 37 and expands in diameter downward, and a large diameter tubular portion 39 that is connected to the large taper tubular portion 38. The valve body tubular portion 30b is press-fitted into the fitting cylindrical portion 34 of the valve body base 30a, and is integrated with the valve body base 30a with its lower end abutting against the upper surface of the large diameter cylindrical portion 35.

[0022] The valve body base 30a and the valve body tubular portion 30b are formed by cutting and then joined together. A material with a relatively low hardness, such as brass, is used for the portion of the valve body 3 that sits on the valve seat 20, taking into consideration sealing properties and abrasion resistance. However, materials such as brass are relatively expensive, so if the valve body 3 is formed from a single material (for example, brass), the material cost will be high. In contrast, according to this embodiment, the valve body base 30a is made of SUS and the portion that sits on the valve seat 20 is the valve body tubular portion 30b, which can reduce the material cost. In addition, since the valve body tubular portion 30b fits only into the fitting cylindrical portion 34, the machining accuracy of the outer diameter of the medium diameter cylindrical portion 33 can be lower than the machining accuracy of the outer diameter of the fitting cylindrical portion 34, which can reduce the processing cost. However, the valve body 3 can also be made integral. The accommodated portion is a portion of the valve body 3 that is located closer to the biasing device 4 than the valve seat 20 (this is the same in the embodiments described below), but is not limited thereto.

[0023] In this embodiment, the outer periphery of the small diameter cylindrical portion 37 of the valve body cylindrical portion 30b is slidable relative to the third inner periphery portion 21c, and the outer periphery of the flange portion 36 is slidable relative to the fifth inner periphery portion 21e.

[0024] In addition, the medium diameter cylindrical portion 33 is located in the valve chamber VC, and the large tapered cylindrical portion 38 of the valve body cylindrical portion 30b can abut against the valve seat 20 around the entire circumference. When the valve body 3 is displaced in the direction from the expansion chamber S2 toward the pressure chamber S1, the large tapered cylindrical portion 38 is seated on the valve seat 20, thereby restricting the flow of refrigerant passing through the orifice. This state is called a non-communicating state. However, even when the valve body 3 is seated on the valve seat 20, a restricted amount of refrigerant may flow. On the other hand, when the valve body 3 is displaced in the direction from the pressure chamber S1 toward the expansion chamber S2, the large tapered cylindrical portion 38 is separated from the valve seat 20, thereby increasing the flow of refrigerant passing through the orifice. This state is called a communicating state.

[0025] A thin, annular seal 47 made of synthetic resin (e.g., PTFE) is placed on the upper surface of the small tapered portion 32 and is further sandwiched and held by the tapered lower end surface of a hollow cylindrical collar 48 that fits into the small diameter cylindrical portion 31. This gives the seal 47 an umbrella shape that expands in diameter as it extends downward, following the shape of the small tapered portion 32.

[0026] The outer periphery of the seal 47 is slidable relative to the second inner periphery 21b, and seals between the valve body 3 and the collar 48, and between the valve body 3 and the second inner periphery 21b (i.e., the pressure chamber S1). The internal space of the second inner periphery 21b above the seal 47 and the collar 48 is called the back pressure chamber BC. The small diameter cylindrical portion 31 and the collar 48 can be fixed by screwing their threads together or by press-fitting their cylindrical surfaces together. The lower surface exposed to the valve chamber VC through the gap between the second inner periphery 21b of the seal 47 and the valve body 3 constitutes a high pressure receiving portion, and the upper surface of the small diameter cylindrical portion 31 and the collar 48, and the upper surface exposed to the back pressure chamber BC through the gap between the second inner periphery 21b of the seal 47 and the collar 48 constitute a low pressure receiving portion. Therefore, the high pressure receiving portion receives the pressure of the valve chamber VC, and the low pressure receiving portion receives the pressure of the back pressure chamber BC.

[0027] The seal 47 and the collar 48 form a partition that divides the pressure chamber S1 of the through hole 21 into a valve chamber VC on the valve seat 20 side and a back pressure chamber BC on the power element 8 side. However, the partition is not limited to the seal 47 and the collar 48, and if the collar 48 has a sealing function, for example, the seal 47 can be omitted.

[0028] 1 and 2, a short cylindrical actuation rod 5 is disposed radially inside the first inner circumferential portion 21a to the second inner circumferential portion 21b, and is slidable relative to the first inner circumferential portion 21a. The lower end of the actuation rod 5 abuts against the upper end of the small diameter cylindrical portion 31, and the upper end of the actuation rod 5 abuts against the lower end of a cylindrical portion 84b of a stopper member 84 described later. The lower end of the actuation rod 5 may abut against the collar 48. Here, the transmission portion is the actuation rod 5 abutting against the cylindrical portion 84b of the stopper member 84 of the power element 8, and a portion of the valve body 3 abutting against the actuation rod 5, which is located closer to the power element 8 than the valve seat 20.

[0029] The actuating rod 5 receives the driving force of the stopper member 84 and can press the valve body 3 in the valve opening direction against the biasing force of the biasing device 4. When the actuating rod 5 moves downward, the valve body 3 moves away from the valve seat 20, and the expansion valve 1 is in the open state.

[0030] 498 1, the biasing device (also referred to as the biasing portion) 4 has a coil spring 41 made of a wire rod with a circular cross section wound in a spiral shape, a disk-shaped female screw member 42, a male screw member 43, and a retaining member 44, and has the function of biasing the valve body 3 toward the valve seat 20. The cap 45 is attached to the valve body 2 as described below, and protects the male screw member 43 and the like.

[0031] The cylindrical holding member 44 has a male thread 44a on the outer periphery at the upper end, and is fixed to the lower end of the valve body 2 by screwing the male thread 44a into the female thread 21h formed on the sixth inner periphery portion 21f.

[0032] The male screw member 43 arranged inside the holding member 44 has a male screw 43a on the upper end side, a sealing portion 43b on the lower end side, and a flange-shaped portion 43c formed at an intermediate position. The lower surface of the flange-shaped portion 43c abuts against the upper surface of the bottom portion 44b of the holding member 44, and the sealing portion 43b is inserted into a through opening 44c formed in the bottom portion 44b of the holding member 44. A seal member 46 such as an O-ring arranged in the sealing portion 43b seals the through opening 44c and the sealing portion 43b so as to be capable of relative rotation, thereby preventing refrigerant leakage.

[0033] The upper end of the coil spring 41 abuts against the lower surface of the valve body 3, and the lower end of the coil spring 41 abuts against the upper surface of the female screw member 42, with the coil spring 41 biasing them in a direction separating them. A female screw 42a formed on the inner periphery of the female screw member 42 is screwed into a male screw 43a formed on the outer periphery of the upper end side of the male screw member 43.

[0034] By rotating the lower end of the sealing portion 43b, which penetrates the through opening 44c of the retaining member 44 and is exposed from its lower end, using a tool not shown, the female screw member 42 rises and falls along the axis L relative to the male screw member 43, thereby making it possible to adjust the elastic force applied to the valve body 3 from the coil spring 41.

[0035] After adjustment of the coil spring 41, the cap 45 is attached to the lower end of the holding member 44 by screw fastening or the like, and covers and protects the lower end of the sealing portion 43b exposed from the holding member 44.

[0036] Next, the power element 8 will be described. The power element 8 is provided in a portion of the valve body 2 facing the valve seat 20 across the pressure chamber S1, and has the function of generating a driving force to be transmitted to the valve element 3. The power element 8 includes an upper cover member 82, a diaphragm 83, a receiving member 86, and a stopper member 84.

[0037] The top cover member 82 is formed, for example, by press-molding a metal plate. The top cover member 82 has a flattened dome shape with a raised center, and an opening 82a is formed through the center. The lower end of a capillary tube 81 is fixed to the opening 82a by brazing or welding. The other end of the capillary tube 81 is connected to a temperature sensing tube (not shown). The temperature sensing tube is attached to the outlet piping of the evaporator.

[0038] The receiving member 86 facing the upper cover member 82 is formed, for example, by press-molding a metal plate. The receiving member 86 has an annular lower flange portion 86a and a cylindrical portion 86b that is connected to the inner periphery of the lower flange portion 86a and faces downward. A female thread 86c is formed on the inner periphery of the cylindrical portion 86b.

[0039] Diaphragm 83, which is disposed between upper cover member 82 and receiving member 86, is made of a thin, flexible metal (e.g., SUS) plate material, and has an outer diameter approximately the same as the outer diameters of upper cover member 82 and receiving member 86. Diaphragm 83 has a concentrically uneven shape formed thereon, and has a flexible structure.

[0040] The stopper member 84 is formed by connecting a disk portion 84a and a cylindrical portion 84b formed at the center of the lower surface of the disk portion 84a. The lower surface of the disk portion 84a faces the pressure equalizing hole 24 that opens at the upper end of the valve body 2. The cylindrical portion 84b is fitted into the first inner peripheral portion 21a of the valve body 2 with a predetermined gap, and the upper end of the working rod 5 abuts against the lower surface of the cylindrical portion 84b. The gap formed between the surface of the stopper member 84 and the opposing surface of the valve body 2 is called a gap path CP, and the refrigerant introduced into the pressure equalizing hole 24 is led to the back pressure chamber BC through the gap path CP and the gap between the first inner peripheral portion 21a and the outer periphery of the working rod 5. The pressure equalizing hole 24 and the gap path CP form an introduction path.

[0041] Furthermore, the top cover member 82, the diaphragm 83, and the receiving member 86 are each formed by press molding, and are integrated by overlapping their outer peripheries and circumferentially welding the outer peripheries by, for example, TIG welding, laser welding, plasma welding, etc. The top cover member 82 and the receiving member 86 form the opening, i.e., a case that covers the through hole 21.

[0042] A working gas is sealed inside the upper space UC surrounded by the upper cover member 82 and the diaphragm 83, the temperature sensing bulb, and the capillary tube 81 connecting the upper space UC and the temperature sensing bulb.

[0043] When assembling the power element 8, the upper surface of the stopper member 84 is brought into contact with the lower surface of the diaphragm 83, and the male thread 86c of the cylindrical portion 86b of the receiving member 86 is screwed into the male thread 2a formed on the outer periphery of the upper end of the valve body 2, thereby fixing the power element 8 to the valve body 2. The lower end of the stopper member 84 is in contact with the upper end of the actuation rod 5.

[0044] At this time, the upper space UC and the lower space LC of the power element 8 are separated and isolated by the diaphragm 83, and the diaphragm 83 deforms based on the pressure difference between the upper space UC and the lower space LC. In this state, the lower space LC of the power element 8 communicates with the pressure equalizing hole 24.

[0045] (Expansion valve operation) An example of the operation of the expansion valve 1 will be described with reference to Fig. 1. The refrigerant pressurized by a compressor (not shown) is supplied to a condenser (not shown) via a high-pressure pipe, where it is condensed and liquefied, and then sent to the expansion valve 1 via a primary pipe H1. The refrigerant adiabatically expanded by the expansion valve 1 is sent to an evaporator (not shown) via a secondary pipe H2, where it exchanges heat with the air flowing around it. The refrigerant is then returned from the evaporator to the compressor via an outlet pipe.

[0046] At this time, the pressure of the refrigerant in the outlet piping of the evaporator is transmitted via the pressure equalizing tube to the pressure equalizing hole 24 of the expansion valve 1, and is further transmitted to the lower space LC of the power element 8. Meanwhile, the temperature of the refrigerant in the outlet piping is transmitted to the temperature sensing tube, causing the gas-liquid state and pressure of the gas in the temperature sensing tube to change, and this is transmitted via the capillary tube 81 to the upper space UC of the power element 8. The diaphragm 83 is displaced vertically due to the pressure difference between the upper space UC and the lower space LC.

[0047] In the expansion valve 1, high-pressure refrigerant from the condenser is supplied to the valve chest VC via a first flow path 22.

[0048] When the valve element 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 to the evaporator through the second flow path 23 is restricted. On the other hand, when the valve element 3 is separated from the valve seat 20 (in a communicating state), the flow rate of the refrigerant sent from the valve chamber VC to the evaporator through the second flow path 23 increases. The expansion valve 1 is switched between the closed state and the open state by transmitting a driving force between the stopper member 84 and the valve element 3 by the operating rod 5.

[0049] When the internal pressure of the upper space UC decreases relative to the internal pressure of the lower space LC, the diaphragm 83 rises, and the valve body 3 moves upward together with the stopper member 84 and the operating rod 5 in response to the biasing force of the coil spring 41. On the other hand, when the internal pressure of the upper space UC increases relative to the internal pressure of the lower space LC, the diaphragm 83 and the stopper member 84 are pressed downward, and the operating rod 5 moves downward to press down the valve body 3. In this manner, the expansion valve 1 is switched between the open state and the closed state.

[0050] Furthermore, when the flow rate of the refrigerant sent from the expansion valve 1 to the evaporator changes, the temperature and pressure flowing in the outlet piping also change. The internal pressure of the lower space LC and the upper space UC changes accordingly, and the amount of drive of the working rod 5 by the power element 8 also changes. In other words, in the expansion valve 1, the amount of refrigerant supplied from the expansion valve 1 to the evaporator is automatically adjusted according to the temperature and pressure of the refrigerant returning to the expansion valve 1 from the evaporator.

[0051] According to this embodiment, a single actuating rod 5 is disposed between the stopper member 84 and the valve body 3 along the axis L. Therefore, if a plurality of actuating rods 5 are disposed around the axis L, the inclination of the actuating rod 5 with respect to the axis L that may occur due to an error (variation) in the length of each actuating rod 5 can be suppressed, so that the friction between the sliding parts can be suppressed, thereby improving the valve controllability at the time of small opening. In addition, by changing the actuating rod 5 to one with a different length, the valve opening timing and the maximum flow rate can be adjusted.

[0052] Moreover, according to this embodiment, it is possible to cancel the effect of the high-pressure refrigerant in the first flow path 22. If the back pressure chamber BC were not connected to the pressure equalizing hole 24, a biasing force (called a high-pressure influence force) would act on the valve body 3 in the valve opening direction due to the pressure difference between the first flow path 22 and the second flow path 23.

[0053] If this biasing force is too large, there is a risk of problems such as an increase in the amount of refrigerant or hunting due to the valve opening proceeding beyond a specified amount, and therefore it is necessary to take measures such as increasing the elastic force of the coil spring 41. However, if the elastic force of the coil spring 41 is increased in accordance with the high pressure influence, it becomes necessary to improve the rigidity of each part, which may lead to an increase in the size and weight of the expansion valve 1. Such high pressure influence tends to increase as the diameter (orifice diameter) of the valve seat 20 increases.

[0054] Therefore, in this embodiment, a seal 47 and a collar 48 are attached to the upper end of the valve body 3, and the pressure inside the valve chamber VC is utilized to generate an upward biasing force (called a canceling force) on the valve body 3, thereby canceling the high-pressure influence.

[0055] Specifically, the high pressure of the refrigerant in the first flow passage 22 is transmitted through the valve chamber VC to the seal 47 constituting the high pressure receiving portion, and as a result, a force in a direction to close the valve element 3 is applied through the seal 47 and the collar 48. Meanwhile, since the back pressure chamber BC is in communication with the pressure equalizing hole 24, a pressure approximately equal to the low pressure of the refrigerant in the second flow passage 23 is transmitted to the back pressure chamber BC. When the pressure loss of the evaporator is small enough to be ignored, the refrigerant pressure in the pressure equalizing hole 24, i.e., on the upper surface of the collar 48, is approximately equal to the refrigerant pressure in the second flow passage 23.

[0056] As a result, the back pressure chamber BC side across the seal 47 becomes low pressure, and the opposing valve chamber VC side becomes high pressure, which causes a force to close the valve element 3 via the collar 48. The force in the valve opening direction and the force in the valve closing direction due to the pressure of the refrigerant in the first flow path 22 act on the valve element 3, canceling out the high pressure influence.

[0057] Here, if the inner diameter of the second inner circumferential portion 21b with which the outer periphery of the seal 47 contacts is made equal to the inner diameter of the valve seat 20 at the lower end of the third inner circumferential portion 21c, there is a problem that the cancellation of the high pressure influence becomes too strong. Specifically, as the pressure of the refrigerant in the first flow passage 22 becomes higher relative to the pressure of the refrigerant in the second flow passage 23, the force urging the valve element 3 in the valve closing direction tends to become stronger than the force urging the valve element 3 in the valve opening direction, which hinders highly accurate valve control.

[0058] Therefore, in this embodiment, the inner diameter of the second inner circumferential portion 21b is made smaller than the inner diameter of the third inner circumferential portion 21c, i.e., the valve seat 20. When the inner diameter of the second inner circumferential portion 21b is A and the inner diameter of the valve seat 20 is B, A>B. Since the force due to the pressure difference of the refrigerant acting on the valve element 3 along the axial direction is the pressure multiplied by the cross-sectional area, by making the cross-sectional area of ​​the second inner circumferential portion 21b smaller than the cross-sectional area of ​​the valve seat 20, the force in the valve closing direction applied to the valve element 3 by the pressure of the refrigerant in the first flow path 22 is made smaller than the force in the valve opening direction, thereby making it possible to appropriately cancel the high-pressure influence and perform highly accurate valve control.

[0059] Second embodiment Fig. 3 is an enlarged longitudinal sectional view of the valve body and its vicinity of the expansion valve 1A according to the second embodiment. Fig. 4 is an enlarged view of the collar 48A and its vicinity. The expansion valve 1A of this embodiment has different configurations of the valve body 3A, collar 48A, and actuating rod 5A, and the other configurations are the same as those of the first embodiment. Therefore, the same reference numerals are used and the repeated explanation is omitted.

[0060] In this embodiment, a collar 48A is disposed between the stopper member 84 and the actuation rod 5A. The collar 48A is formed by connecting an upper cylindrical portion 48Aa, the upper end of which abuts against the lower end of the stopper member 84, a conical portion 48Ab, which is connected to the upper cylindrical portion 48Aa and expands in diameter downward, and a lower cylindrical portion 48Ac, which is connected to the conical portion 48Ab. The collar 48A has a female threaded hole 48Ad at the center of the lower end, and the periphery of the female threaded hole 48Ad is a tapered surface that expands in diameter downward. The lower cylindrical portion 48Ac is slidably fitted to the second inner peripheral portion 21b. In this embodiment, the second inner peripheral portion 21b constitutes the inner peripheral portion of the back pressure chamber.

[0061] The actuation rod 5A has a male threaded portion 5Aa, a small tapered portion 5Ab that is connected to the male threaded portion 5Aa and expands in diameter as it goes downward, and a cylindrical portion 5Ac that is connected to the small tapered portion 5Ab. After the seal 47 is installed on the small tapered portion 5Ab, the collar 48A is brought close to the small tapered portion 5Ab, and the female threaded hole 48Ad is screwed into the male threaded portion 5Aa, so that the seal 47 is sandwiched between the collar 48A and the actuation rod 5A and held in an umbrella shape, and the outer periphery of the seal 47 slidably abuts against the second inner peripheral portion 21 of the valve body 2. Here, the seal 47 and the collar 48A form a partition portion. However, the partition portion is not limited to the seal 47 and the collar 48A, and if the collar 48A has a sealing function, for example, the seal 47 can be omitted. The transmission portion is made up of the collar 48A that abuts against the cylindrical portion 84b of the stopper member 84 of the power element 8, and the operating rod 5A that is disposed between the collar 48A and the valve body 3A.

[0062] The valve body 3A is formed by connecting a truncated cone-shaped upper valve body part 3Aa and a cylindrical lower valve body part 3Ab. The upper end of a coil spring 41 abuts against the lower surface of the lower valve body part 3Ab. A circular recess 3Ac is formed in the center of the upper surface of the upper valve body part 3Aa, and the lower end of the actuation rod 5A fits into the circular recess 3Ac. The outer periphery of the upper valve body part 3Aa is seated on the valve seat 20.

[0063] In this embodiment, the downward biasing force of the stopper member 84 is transmitted to the valve body 3A via the collar 48A and the actuation rod 5A. Since the axial force acting between the valve body 3A and the actuation rod 5A acts only in the direction in which they approach each other, the valve body 3A and the actuation rod 5A are not joined together, but may be joined together by welding or brazing.

[0064] According to this embodiment, when the seal 47 receives high pressure from the pressure chamber side, an upward biasing force is transmitted to the stopper member 84 via the collar 48A, but similar to the first embodiment, the seal 47 and the collar 48A can cancel the high pressure influence.

[0065] Third embodiment 5 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1B according to the third embodiment. The expansion valve 1B of this embodiment differs from the second embodiment in that the collar and seal are omitted, and the actuating rod 5B abuts against the stopper member 84 and the valve body 3A. The rest of the configuration is the same as that of the second embodiment, including the canceling action of the high pressure influence, so the same reference numerals are used and repeated explanations will be omitted.

[0066] In this embodiment, the actuation rod 5B is formed by coaxially connecting a first cylindrical portion 5Ba, a second cylindrical portion 5Bb having a diameter larger than that of the first cylindrical portion 5Ba, and a third cylindrical portion 5Bc having a diameter smaller than that of the second cylindrical portion 5Bb. The second cylindrical portion 5Bb is slidably fitted into the second inner peripheral portion 21b of the valve body 2, and a circumferential groove 5Bd is formed at a middle position on the outer periphery of the second cylindrical portion 5Bb. An O-ring OR is disposed in the circumferential groove 5Bd to seal between the second cylindrical portion 5Bb and the second inner peripheral portion 21b. The O-ring OR, which receives high pressure from the pressure chamber side, abuts against the side wall of the circumferential groove 5Bd, and an upward biasing force is transmitted to the actuation rod 5B. In this embodiment, the O-ring OR performs the function of the seal (partition portion) of the above-mentioned embodiment, and performs a canceling action of the high pressure influence by the pressure difference between the top and bottom of the O-ring OR. Here, the transmission portion is the operating rod 5B disposed between the cylindrical portion 84b of the stopper member 84 of the power element 8 and the valve body 3A.

[0067] The lower end of the actuating rod 5B fits into the circular recess 3Ac of the valve body 3A. In this embodiment, the downward biasing force of the stopper member 84 is transmitted to the valve body 3A via the actuating rod 5B.

[0068] (Fourth embodiment) 6 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1C according to the fourth embodiment. The expansion valve 1C of the present embodiment differs from the third embodiment in that a valve body 2C, an actuating rod 5C, and a stopper member 84C are different, and the other configurations, including the canceling action of the high pressure influence, are the same as those of the third embodiment, so that the same reference numerals are used and repeated explanations are omitted.

[0069] The valve body 2C differs in that the second circumferential portion is omitted and the first circumferential portion 21Ca and the third circumferential portion 21Cc are connected in the through hole 21C. In this embodiment, the first inner circumferential portion 21Ca constitutes the inner circumferential portion of the back pressure chamber. The other configurations of the valve body 2C are the same as those of the above-mentioned embodiment, so that the repeated explanation will be omitted.

[0070] The stopper member 84C is formed by connecting a disk portion 84Ca and a cylindrical portion 84Cb formed at the center of the lower surface of the disk portion 84Ca, and a circumferential groove 84Cc is formed at the middle position on the outer periphery of the cylindrical portion 84Cb. The cylindrical portion 84Cb slidably fits into the first circumferential portion 21Ca. An O-ring OR is disposed in the circumferential groove 84Cc to seal between the cylindrical portion 84Cb and the second inner circumferential portion 21b.

[0071] The O-ring OR, which receives high pressure from the pressure chamber, contacts the side wall of the circumferential groove 84Cc, and the upward biasing force is transmitted to the stopper member 84C. The O-ring OR functions as a seal (partition portion) in the first embodiment and the like, and cancels the high pressure influence due to the pressure difference between the top and bottom of the O-ring OR. In this embodiment, the back pressure chamber BC is defined between the cylindrical portion 84Cb above the O-ring OR and the second inner peripheral portion 21b.

[0072] The actuating rod 5C has a simple cylindrical shape, and the lower end of the actuating rod 5C fits into the circular recess 3Ac of the valve body 3A, and the upper end of the actuating rod 5C abuts against the lower end of the stopper member 84C. In this embodiment, the downward biasing force of the stopper member 84C is transmitted to the valve body 3A via the actuating rod 5C. Here, the transmission part is the actuating rod 5C arranged between the cylindrical portion 84Cb of the stopper member 84C of the power element 8 and the valve body 3A.

[0073] The expansion valve of the above embodiment may be applied to an internal pressure equalizing type. An example of the internal pressure equalizing type is an expansion valve described with reference to FIG.

[0074] Fifth embodiment 7 is an enlarged longitudinal sectional view showing the vicinity of the valve body of an expansion valve 1D according to the fifth embodiment. The expansion valve 1D of this embodiment differs from the fourth embodiment in the shapes of a valve body 2D and a valve body 3D, and further includes a spring receiving member 47D. The rest of the configuration, including the canceling action of the high pressure influence, is the same as that of the fourth embodiment, so the same reference numerals are used and repeated explanations will be omitted.

[0075] The expansion valve 1D is a so-called internal pressure equalizing type, and therefore the lower end of the pressure equalizing hole 24D of the valve body 2D is connected to the expansion chamber S2. The through hole 21D of the valve body 2D has, from the upper end side, a first inner circumferential portion 21Da, a second inner circumferential portion 21Db, a third inner circumferential portion 21Dc that forms the pressure chamber S1 and the valve chamber VC therein, and a fourth inner circumferential portion 21Dd that forms the expansion chamber S2 therein. An O-ring OR arranged in a circumferential groove 84Cc of a cylindrical portion 84Cb of a stopper member 84C abuts against the first inner circumferential portion 21Da, and an operating rod 5C is inserted into the second inner circumferential portion 21Db. The inner diameter of the first inner circumferential portion 21Da is larger than the inner diameter of the second inner circumferential portion 21Db that constitutes the back pressure chamber inner circumferential portion and smaller than the inner diameter of the third inner circumferential portion 21Dc that constitutes the valve chamber inner circumferential portion. The valve seat 20 is formed at the lower end of the third inner circumferential portion 21Dc. The other configurations of the valve body 2D are the same as those of the above-mentioned embodiment, so duplicated explanations will be omitted. Here, the transmission portion is the operating rod 5C arranged between the cylindrical portion 84Cb of the stopper member 84C of the power element 8 and the valve body 3D.

[0076] In this embodiment, the back pressure chamber BC is defined between the cylindrical portion 84Cb of the stopper member 84C above the O-ring OR and the first inner peripheral portion 21Da. A gap formed between the surface of the stopper member 84C and the opposing surface of the valve body 2D is called a gap path CP, and the pressure equalizing hole 24 and the gap path CP form an introduction path. The refrigerant introduced from the expansion chamber S2 to the pressure equalizing hole 24D is led to the back pressure chamber BC via the gap path CP and the gap between the first inner peripheral portion 21Da and the outer periphery of the cylindrical portion 84Cb.

[0077] The O-ring OR, which receives high pressure from the pressure chamber, comes into contact with the side wall of the circumferential groove 84Cc, and the upward biasing force is transmitted to the stopper member 84C. The O-ring OR performs the function of a seal (partition portion) of the first embodiment and the like described above, and cancels the high-pressure influence due to the pressure difference between the top and bottom of the O-ring OR.

[0078] A recess 3Dc is formed at the upper end of the cylindrical valve body 3D, into which the lower end of the actuation rod 5C fits. The lower end 3Dd of the valve body 3D, which protrudes in a semi-elliptical sphere shape, is supported by a central recess of a spring receiving member 47D placed on the upper end of the coil spring 41 within the fourth inner circumferential portion Dd. In this embodiment, the downward biasing force of the stopper member 84C is transmitted to the valve body 3D via the actuation rod 5C.

[0079] Sixth embodiment 8 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1E according to the sixth embodiment. The expansion valve 1E of the present embodiment differs from the fifth embodiment in the shape of a stopper member 84E. Other configurations, including the canceling action of the high pressure influence, are the same as those of the fifth embodiment, so the same reference numerals are used and repeated explanations are omitted.

[0080] The stopper member 84E is composed of a disk portion 84Ea, a large cylindrical portion 84Eb formed in the center of the lower surface of the disk portion 84Ea, and a small cylindrical portion 84Ec connected to the lower end of the large cylindrical portion 84Eb.

[0081] The large cylindrical portion 84Eb is slidably inserted into the first inner periphery 21Da of the valve body 2D, and the lower end of the small cylindrical portion 84Ec is slidably inserted into the second inner periphery 21Db. An O-ring OR is disposed on the step between the outer periphery of the small cylindrical portion 84Ec in the first inner periphery 21Da and the first inner periphery 21Da, sealing the gap between the small cylindrical portion 84Ec and the first inner periphery 21Da. The upper end of the actuating rod 5C abuts against the lower end of the small cylindrical portion 84Ec. Here, the transmission portion is the actuating rod 5C disposed between the cylindrical portion 84Eb of the stopper member 84E of the power element 8 and the valve body 3D.

[0082] In this embodiment, the back pressure chamber BC is defined between the large cylindrical portion 84Eb above the O-ring OR and the first inner circumferential portion 21Da. In this embodiment, the first inner circumferential portion 21Da constitutes the inner circumferential portion of the back pressure chamber. The refrigerant introduced from the expansion chamber S2 to the pressure equalizing hole 24D is led to the back pressure chamber BC.

[0083] The O-ring OR, which receives high pressure from the pressure chamber, comes into contact with the step between the large cylindrical portion 84Eb and the small cylindrical portion 84Ec, and the upward biasing force is transmitted to the stopper member 84E. The O-ring OR performs the function of the seal (partition portion) of the first embodiment and the like described above, and cancels the high pressure influence due to the pressure difference between the top and bottom of the O-ring OR.

[0084] Seventh embodiment 9 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1F according to the seventh embodiment. The expansion valve 1F of this embodiment differs from the fifth embodiment in that a part of the stopper member is separated to form a sealing tube member. The other configurations, including the canceling action of the high pressure influence, are the same as those of the fifth embodiment, so the same reference numerals are used and repeated explanations are omitted.

[0085] The stopper member 84F is formed by connecting a disk portion 84Fa and a cylindrical portion 84Fb formed in the center of the lower surface of the disk portion 84Fa.

[0086] The seal tube member 87F has a seal cylinder portion 87Fa on the upper end side and a seal column portion 87Fb on the lower end side. The inner periphery of the seal cylinder portion 87Fa is fitted into the outer periphery of the cylinder portion 84Fb, and the stopper member 84F and the seal tube member 87F are displaced integrally in the axial direction. The lower end of the seal column portion 87Fb abuts against the upper end of the actuation rod 5C. An O-ring OR is disposed in a circumferential groove 87Fc formed on the outer periphery of the seal column portion 87Fb.

[0087] A seal cylinder member 87F is slidably fitted to the first inner circumferential portion 21Da of the valve body 2D. An O-ring OR disposed in a circumferential groove 87Fc seals between the seal cylinder member 87F and the first inner circumferential portion 21Da. Here, the transmission part is the seal cylinder portion 87F connected to the cylindrical portion 84Fb of the stopper member 84F of the power element 8, and the operating rod 5C disposed between the seal cylinder portion 87F and the valve body 3D.

[0088] In this embodiment, the back pressure chamber BC is defined between the outer periphery of the sealing cylinder member 87F above the O-ring OR and the first inner circumferential portion 21Da. The low pressure refrigerant introduced from the expansion chamber S2 to the pressure equalizing hole 24D is guided to the back pressure chamber BC through the gap path CP and the gap between the first inner circumferential portion 21Da and the sealing cylinder member 87F.

[0089] The O-ring OR, which receives high pressure from the pressure chamber side, comes into contact with the side wall of the circumferential groove 87Fc, and the upward biasing force is transmitted to the stopper member 84F via the sealing cylinder member 87F. The O-ring OR performs the function of the seal (partition portion) of the first embodiment and the like described above, and cancels the high-pressure influence due to the pressure difference between the top and bottom of the O-ring OR.

[0090] Eighth embodiment 10 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1G according to the eighth embodiment. The expansion valve 1G of this embodiment differs from the seventh embodiment in that a seal holder 87G is provided instead of the sealing cylinder member, and in that a stopper member 84G has a different shape. Other configurations, including the canceling action of the high pressure influence, are the same as those of the seventh embodiment, and therefore the same reference numerals are used and repeated explanations will be omitted.

[0091] The stopper member 84G is formed by connecting a disk portion 84Ga and an elongated cylindrical portion 84Gb formed at the center of the lower surface of the disk portion 84Ga. The lower end of the cylindrical portion 84Gb abuts against the upper end of the actuation rod 5C. Here, the transmission portion is the actuation rod 5C disposed between the cylindrical portion 84Gb of the stopper member 84G of the power element 8 and the valve body 3D.

[0092] An O-ring OR with a cylindrical portion 84Gb inserted therein is disposed in the first inner circumferential portion 21Da of the valve body 2D, and a seal holder 87G is fixed in the first inner circumferential portion 21Da above the O-ring OR by fitting or by a fixing member such as a screw. The cylindrical portion 84Gb is slidably fitted into a through hole 87Ga formed in the center of the seal holder 87G and the inner circumferential portion of the O-ring OR. A gap is provided between the seal holder 87G and the cylindrical portion 84G to allow the refrigerant to pass through. The seal holder 87G preferably has an outer circumferential surface that decreases in diameter from the center in the axial direction downward. In FIG. 10, there is a gap between the lower end surface of the first inner circumferential portion 21Da and the O-ring OR, and this gap allows the O-ring OR to swell when it comes into contact with the refrigerant.

[0093] In this embodiment, the back pressure chamber BC is defined between the first inner circumferential portion 21Da and the cylindrical portion 84Ga above the O-ring OR. When a high pressure is applied from the pressure chamber side, the pressure in the space below the O-ring OR increases, pushing up the cylindrical portion 84Gb, and the urging force is transmitted to the stopper member 84G. The refrigerant introduced from the expansion chamber S2 into the pressure equalizing hole 24D is led to the back pressure chamber BC via the gap path CP and the gap between the first inner circumferential portion 21Da and the seal holder 87G.

[0094] The O-ring OR functions as a seal (partition portion) in the first embodiment and the like, and cancels the high pressure influence due to the pressure difference between the top and bottom of the O-ring OR. In this embodiment, the stopper member 84G slides against the O-ring OR as the stopper member 84G is displaced. Specifically, the stopper member 84G slides against the inner periphery of the O-ring OR. This reduces the input area of ​​the load that causes twisting in the O-ring OR, and as a result, the degree of twisting in the O-ring OR can be reduced.

[0095] Ninth embodiment 11 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1H according to the ninth embodiment. The expansion valve 1H of this embodiment differs from the seventh embodiment in that a seal holder 87H is provided instead of the sealing cylinder member, an annular seal 47H is provided instead of the O-ring OR, and the shape of a stopper member 84H is different. The rest of the configuration, including the canceling action of the high pressure influence, is the same as that of the seventh embodiment, so the same reference numerals are used and repeated explanations will be omitted.

[0096] The stopper member 84H is composed of a disk portion 84Ha and a cylindrical portion 84Hb formed at the center of the lower surface of the disk portion 84Ha. A circular hole 84Hc is formed at the center of the lower end of the cylindrical portion 84Hb, and the periphery of the circular hole 84Hc forms a tapered surface that expands in diameter as it extends downward. The outer periphery of the cylindrical portion 84Hb is slidably inserted into the first inner peripheral portion 21Da of the valve body 2D.

[0097] The seal holder 87H is formed by connecting an upper cylindrical portion 87Ha that is press-fitted (or screwed) into the circular hole 84Hc, and a conical portion 87Hb that is connected to the upper cylindrical portion 87Ha and expands in diameter downward. The circumference of the conical portion 87Hb is a tapered surface that expands in diameter downward. The lower end of the seal holder 87H abuts against the upper end of the working rod 5C. Here, the transmission portion is the seal holder 87H that is connected to the cylindrical portion 84Hb of the stopper member 84H of the power element 8, and the working rod 5C that is arranged between the seal holder 87H and the valve body 3D.

[0098] The seal 47H is sandwiched and held between the tapered surface at the lower end of the stopper member 84H and the conical portion 87Hb of the seal holder 87H, and is formed into an umbrella shape whose diameter increases downward.

[0099] The outer periphery of the seal 47H is slidable relative to the first inner periphery 21Da and seals the gap between the upper cylindrical portion 87Ha and the cylindrical portion 84Hb, and the gap between the cylindrical portion 84Hb and the first inner periphery 21Da. The internal space of the first inner periphery 21Da above the seal 47H is referred to as a back pressure chamber BC. In this embodiment, the first inner periphery 21Da constitutes the inner periphery of the back pressure chamber.

[0100] The refrigerant introduced from the expansion chamber S2 into the pressure equalizing hole 24D is guided to the back pressure chamber BC via the gap path CP and the gap between the first inner circumferential portion 21Da and the cylindrical portion 84Hb.

[0101] When the seal 47H receives high pressure from the pressure chamber side, an upward biasing force is transmitted to the stopper member 84E. The seal 47H exhibits the function of the seal (partition portion) of the first embodiment and the like described above, and exhibits a canceling effect of the high pressure influence due to the pressure difference between the top and bottom of the seal 47H.

[0102] Tenth embodiment Fig. 12 is an enlarged longitudinal sectional view showing the valve body and its vicinity of the expansion valve 1I according to the tenth embodiment. Fig. 13 is an enlarged view showing the seal holder 87I and its vicinity. The expansion valve 1I of this embodiment differs from the seventh embodiment mainly in that an annular seal 47I is provided instead of the O-ring OR, and in the shape of the valve body 2I. Other configurations, including the canceling action of the high pressure influence, are the same as those of the seventh embodiment, and therefore the same reference numerals are used and repeated explanations will be omitted.

[0103] As shown in Fig. 13, the valve body 2I has a body tapered portion 21Ie between the first inner circumferential portion 21Ia and the second inner circumferential portion 21Ib, the diameter of which decreases as it approaches the bottom. The other configuration of the valve body 2I is the same as that of the seventh embodiment, so a duplicated description will be omitted. However, the transmission portion is the operating rod 5C arranged between the cylindrical portion 84Gb of the stopper member 84G of the power element 8 and the valve body 3D.

[0104] An annular seal 47I is disposed between the first inner circumferential portion 21Ia and the second inner circumferential portion Ib, and is fixed to the valve body 2I by a seal holder 87I. The seal holder 87I is fixed to the first inner circumferential portion 21Ia by fitting, or by a fixing member such as a screw. A cylindrical portion 84Gb of a stopper member 84G is slidably inserted into the seal holder 87I and the inner circumferential portion of the seal 47I. A gap is provided between the seal holder 87I and the cylindrical portion 84G to allow the refrigerant to pass through. Before assembly, the seal 47I has an umbrella shape that narrows downward, and has the same umbrella shape after assembly.

[0105] The outer periphery of the seal 47I abuts against the first inner circumferential portion 21Ia. The inner periphery of the seal 47I slidably abuts against the outer periphery of the cylindrical portion 84Gb of the stopper member 84G, sealing the gap between the cylindrical portion 84Gb and the first inner circumferential portion 21Ia. The internal space of the first inner circumferential portion 21Ia above the seal 47I is referred to as a back pressure chamber BC. In this embodiment, the first inner circumferential portion 21Ia constitutes the inner periphery of the back pressure chamber.

[0106] The seal retainer 87I preferably has an outer circumferential surface whose diameter decreases from the axial center downward.

[0107] The refrigerant introduced from the expansion chamber S2 into the pressure equalizing hole 24D is guided to the back pressure chamber BC via the gap path CP and the gap between the first inner circumferential portion 21Ia and the seal holder 87G.

[0108] When high pressure is applied from the pressure chamber side, the seal 47H is displaced upward and the cylindrical portion 84Ga is pushed up, and the biasing force is transmitted to the stopper member 84E. The seal 47I functions as a partition, and the pressure difference between the top and bottom of the seal 47I cancels the influence of the high pressure.

[0109] The expansion valve of the above embodiment may be applied to an external pressure equalizing type. An example of the external pressure equalizing type is the expansion valve described with reference to Figs.

[0110] This specification includes the disclosure of the following inventions. (First aspect) a valve body including a valve seat, a pressure chamber formed on a primary side of the valve seat, a first flow passage communicating with the pressure chamber and having one end opening to the outside, an expansion chamber formed on a secondary side of the valve seat, and a second flow passage communicating with the expansion chamber and having one end opening to the outside; a valve body that is seated on the valve seat in a direction from the expansion chamber to the pressure chamber and moves away from the pressure chamber in a direction from the pressure chamber to the expansion chamber, the valve body including an accommodated portion that is accommodated in the expansion chamber when seated on the valve seat; a biasing portion that biases the valve body toward the valve seat; a power element provided in a portion of the valve body facing the valve seat across the pressure chamber, the power element generating a driving force that moves the valve body in a direction away from the valve seat; A transmission portion disposed along an axis of the valve seat and configured to transmit a driving force of the power element to the accommodated portion; a partition part that is movably provided integrally with the transmission part and divides the pressure chamber into a valve chamber on the valve seat side and a back pressure chamber on the power element side; An introduction passage that introduces the fluid that has flowed out to the second flow passage into the back pressure chamber. An expansion valve characterized by:

[0111] (Second aspect) The accommodated portion is a portion of the valve body that is located on the biasing portion side from the valve seat. An expansion valve according to a first aspect, characterized in that:

[0112] (Third aspect) the valve body has a through hole with a circular cross section extending along an axis of the expansion valve, a back pressure chamber circumferential portion constituting the back pressure chamber is formed in a part of the through hole, a valve chamber circumferential portion constituting the valve chamber is formed in another part of the through hole, and an inner diameter of the back pressure chamber circumferential portion is smaller than an inner diameter of the valve chamber circumferential portion. An expansion valve according to a first or second aspect, characterized in that

[0113] (Fourth aspect) The valve seat is formed at an end of the valve chamber periphery. An expansion valve according to a third aspect,

[0114] (Fifth aspect) The transmission portion is an actuating rod that abuts against a cylindrical portion of a stopper member of the power element, and a portion of the valve body that abuts against the actuating rod and is located closer to the power element than the valve seat, the partition portion is a seal disposed between the valve body and an outer periphery of the back pressure chamber, and a collar fixed to the valve body; The seal is deformed into an umbrella shape by being sandwiched between the collar and the valve body. The expansion valve according to the third or fourth aspect,

[0115] (Sixth aspect) The transmission portion includes a collar that abuts against a cylindrical portion of a stopper member of the power element, and an actuating rod that is disposed between the collar and the valve body, The partition includes a seal disposed between the actuation rod and an inner periphery of the back pressure chamber, and the collar fixed to the actuation rod; The seal is deformed into an umbrella shape by being sandwiched between the collar and the actuation rod. The expansion valve according to the third or fourth aspect,

[0116] (Seventh aspect) The transmission part includes a seal holder connected to a cylindrical portion of the stopper member of the power element, and an actuating rod disposed between the seal holder and the valve body, the partition portion is a seal disposed between the seal holder and an inner periphery of the back pressure chamber, The seal is deformed into an umbrella shape by being sandwiched between the seal holder and the stopper member. The expansion valve according to the third or fourth aspect,

[0117] (Eighth aspect) The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is a seal disposed between an outer periphery of the cylindrical portion and an inner periphery of the back pressure chamber, the cylindrical portion is slidably inserted into an inner periphery of a seal presser that is fixed to an inner periphery of the back pressure chamber and comes into contact with the seal, and into an inner periphery of the seal; The expansion valve according to the third or fourth aspect,

[0118] (Ninth aspect) The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, The partition is an O-ring disposed in a circumferential groove of the actuation rod and sealing between the outer periphery of the actuation rod and the periphery of the back pressure chamber. The expansion valve according to the third or fourth aspect,

[0119] (Tenth aspect) The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, The partition portion is an O-ring disposed in a circumferential groove of the cylindrical portion and providing a seal between an outer periphery of the cylindrical portion and an inner periphery of the back pressure chamber. The expansion valve according to the third or fourth aspect,

[0120] (Eleventh aspect) The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is an O-ring that seals between the outer periphery of the cylindrical portion and the periphery of the back pressure chamber, The O-ring abuts against the stopper member. The expansion valve according to the third or fourth aspect,

[0121] (Twelfth aspect) The transmission portion includes a cylindrical seal portion connected to a cylindrical portion of the stopper member of the power element, and an actuating rod disposed between the cylindrical seal portion and the valve body, The partition portion is an O-ring that is disposed in a circumferential groove of the cylindrical seal portion and seals between an outer periphery of the cylindrical seal portion and an inner periphery of the back pressure chamber. The expansion valve according to the third or fourth aspect,

[0122] (Thirteenth aspect) The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is an O-ring disposed between an outer periphery of the cylindrical portion of the stopper member and an inner periphery of the back pressure chamber, The cylindrical portion is slidably inserted into an inner peripheral portion of a seal holder fixed to an inner peripheral portion of the back pressure chamber and in contact with the O-ring, and into an inner peripheral portion of the O-ring. The expansion valve according to the third or fourth aspect, [Explanation of symbols]

[0123] 1~1I: Expansion valve 2, 2D, 2I: Valve body 3, 3A, 3D: Valve body 4: Actuating device 5, 5A, 5B, 5C: Operating rod 8: Power Element 20: Valve seat 22: First flow path 23: Second flow path 24, 24D: Equalizing hole 47, 47H, 47I: Seal 48, 48A: Color 81: Capillary tube 82: Top cover member 83: Diaphragm 84: Stopper member 85: Temperature tube 86: Support member 87H, 87I: Seal holder CP: interstitial passage VC: Valve chamber BC: Back pressure chamber S1: Pressure chamber S2: Expansion chamber OR: O-ring UC: Space above the power element LC: Space under the power element

Claims

1. a valve body including a valve seat, a pressure chamber formed on a primary side of the valve seat, a first flow passage communicating with the pressure chamber and having one end opening to the outside, an expansion chamber formed on a secondary side of the valve seat, and a second flow passage communicating with the expansion chamber and having one end opening to the outside; a valve body that is seated on the valve seat in a direction from the expansion chamber to the pressure chamber and moves away from the pressure chamber in a direction from the pressure chamber to the expansion chamber, the valve body including an accommodated portion that is accommodated in the expansion chamber when seated on the valve seat; a biasing portion that biases the valve body toward the valve seat; a power element provided in a portion of the valve body facing the valve seat across the pressure chamber, the power element generating a driving force that moves the valve body in a direction away from the valve seat; A transmission portion disposed along an axis of the valve seat and configured to transmit a driving force of the power element to the accommodated portion; a partition part that is movably provided integrally with the transmission part and divides the pressure chamber into a valve chamber on the valve seat side and a back pressure chamber on the power element side; An introduction passage that introduces the fluid that has flowed out to the second flow passage into the back pressure chamber. An expansion valve characterized by:

2. The accommodated portion is a portion of the valve body that is located on the biasing portion side from the valve seat.

2. The expansion valve according to claim 1 .

3. the valve body has a through hole with a circular cross section extending along an axis of the expansion valve, a back pressure chamber circumferential portion constituting the back pressure chamber is formed in a part of the through hole, a valve chamber circumferential portion constituting the valve chamber is formed in another part of the through hole, and an inner diameter of the back pressure chamber circumferential portion is smaller than an inner diameter of the valve chamber circumferential portion.

2. The expansion valve according to claim 1 .

4. The valve seat is formed at an end of the valve chamber periphery.

4. The expansion valve according to claim 3.

5. The transmission portion is an actuating rod that abuts against a cylindrical portion of a stopper member of the power element, and a portion of the valve body that abuts against the actuating rod and is located closer to the power element than the valve seat, the partition portion is a seal disposed between the valve body and an outer periphery of the back pressure chamber, and a collar fixed to the valve body; The seal is deformed into an umbrella shape by being sandwiched between the collar and the valve body.

4. The expansion valve according to claim 3.

6. The transmission portion includes a collar that abuts against a cylindrical portion of a stopper member of the power element, and an actuating rod that is disposed between the collar and the valve body, The partition includes a seal disposed between the actuation rod and an inner periphery of the back pressure chamber, and the collar fixed to the actuation rod; The seal is deformed into an umbrella shape by being sandwiched between the collar and the actuation rod.

4. The expansion valve according to claim 3.

7. The transmission part is a seal holder connected to a cylindrical portion of the stopper member of the power element, and an actuation rod disposed between the seal holder and the valve body, the partition portion is a seal disposed between the seal holder and an inner periphery of the back pressure chamber, The seal is deformed into an umbrella shape by being sandwiched between the seal holder and the stopper member.

4. The expansion valve according to claim 3.

8. The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is a seal disposed between an outer periphery of the cylindrical portion and an inner periphery of the back pressure chamber, the cylindrical portion is slidably inserted into an inner periphery of a seal presser that is fixed to an inner periphery of the back pressure chamber and comes into contact with the seal, and into an inner periphery of the seal; 4. The expansion valve according to claim 3.

9. The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, The partition is an O-ring disposed in a circumferential groove of the actuating rod and sealing between the outer periphery of the actuating rod and the periphery of the back pressure chamber.

4. The expansion valve according to claim 3.

10. The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is an O-ring disposed in a circumferential groove of the cylindrical portion and providing a seal between an outer periphery of the cylindrical portion and an inner periphery of the back pressure chamber.

4. The expansion valve according to claim 3.

11. The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is an O-ring that seals between an outer periphery of the cylindrical portion and an inner periphery of the back pressure chamber, The O-ring abuts against the stopper member.

4. The expansion valve according to claim 3.

12. The transmission portion includes a cylindrical seal portion connected to a cylindrical portion of the stopper member of the power element, and an actuating rod disposed between the cylindrical seal portion and the valve body, The partition portion is an O-ring that is disposed in a circumferential groove of the cylindrical seal portion and seals between an outer periphery of the cylindrical seal portion and an inner periphery of the back pressure chamber.

4. The expansion valve according to claim 3.

13. The transmission portion is an actuating rod disposed between a cylindrical portion of a stopper member of the power element and the valve body, the partition portion is an O-ring disposed between an outer periphery of the cylindrical portion of the stopper member and an inner periphery of the back pressure chamber, The cylindrical portion is slidably inserted into an inner peripheral portion of a seal holder fixed to an inner peripheral portion of the back pressure chamber and in contact with the O-ring, and into an inner peripheral portion of the O-ring.

4. The expansion valve according to claim 3.

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