JP6272247B2 - Throttle device and refrigeration cycle - Google Patents

Description

  The present invention provides a throttle device that is provided between a condenser and an evaporator of a refrigeration cycle, decompresses the refrigerant condensed by the condenser, and sends the refrigerant to the evaporator, and a refrigeration cycle using the throttle device About.

  Conventionally, as this type of diaphragm device, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 2008-138812 (Patent Document 1). In this conventional throttle device, the valve opening degree changes according to the differential pressure between the refrigerant pressure on the condenser side (primary side) and the refrigerant pressure on the evaporator side (secondary side). And the conventional diaphragm | throttle device is provided with the filter (strainer) in order to remove the foreign material in the refrigerant | coolant which flows in from a primary side.

JP 2008-138812 A

  Generally, a filter (strainer) of about 80 mesh to 100 mesh is attached in the system of the refrigeration cycle, but foreign matter having a size of about 0.15 to 0.2 mm passes through the filter and flows together with the refrigerant. For this reason, when the clearance between the guide surface for guiding the needle valve and the needle valve is 0.02 to 0.1 mm, foreign matter cannot flow through this clearance. For this reason, a foreign substance may be clogged in the sliding part of a guide surface and a needle valve, and a needle valve may be locked.

  The present invention provides a foreign matter generated in a system due to wear or the like in a throttling device that is provided between a condenser and an evaporator of a refrigeration cycle and decompresses the refrigerant condensed by the condenser and sends the refrigerant to the evaporator. Therefore, it is an object to prevent the needle valve from being locked.

A throttling device according to a first aspect is a throttling device provided between a condenser and an evaporator of a refrigeration cycle, decompressing the refrigerant condensed by the condenser and sending the refrigerant to the evaporator. A main body case constituting a primary chamber to be connected and a secondary chamber connected to the evaporator, and a valve port is formed and disposed between the primary chamber and the secondary chamber in the main body case. a valve seat member, a valve body to vary the degree of opening of the valve port by moving along the axis of the valve port, and a spring member for urging the valve body to the valve port side, the valve port A cylindrical guide member that is coaxially disposed on the secondary chamber side in the main body case, the valve body is inserted therein, and a cylindrical guide surface that is parallel to the axis is formed inside. , point contact between the side surface and the cylindrical guide surface of said valve body, also With the sliding contact portion is a portion in line contact are provided more around said axis, the distance between the side surface and the cylindrical guide surface of the valve body between adjacent sliding contact portion is in the sliding contact portion The guide body is provided as an introduction path through which the refrigerant flows and is wider than a distance between a side surface of the valve body and the cylindrical guide surface, and is formed between the introduction path and the valve seat member, It is characterized by having an open hole for conducting to the outside . In addition, in the claims and the specification, “point, line” of “point contact, line contact” means that the contact portion has a finite area, a finite width, and its area and width are very small. Or it is a concept including being a line.

Throttling device according to claim 2, there is provided a diaphragm device according to claim 1, the guide member is released from the back pressure chamber behind the valve body of the second to open the refrigerant in the secondary chamber-side A hole is formed, and a total area of a cross section in a plane perpendicular to the axis of the introduction path is smaller than an area of the second open hole.

A refrigeration cycle according to a third aspect is characterized in that the throttling device according to the first or second aspect is provided between a condenser and an evaporator.

According to the first aspect of the present invention, the valve body is guided by point contact or line contact between the side surface and the guide surface of the valve body at the plurality of sliding contact portions around the axis, and the adjacent sliding contact portions Since the introduction path having a wider interval between the side surface of the valve body and the guide surface is provided between them, the foreign matter mixed in the refrigerant is guided to the introduction path and flows, so that the valve body can be prevented from being locked.

Moreover, it can be set as the flow path through which a refrigerant | coolant flows into the clearance gap between a guide member and a main body case.

According to invention of Claim 2 , in addition to the effect of Claim 1 , the following effects are acquired. The total area of the cross section of the introduction path is smaller than the area of the opening hole that opens the refrigerant from the back pressure chamber behind the valve body to the secondary chamber side, so that the flow rate of the refrigerant flowing from the introduction path into the back pressure chamber On the other hand, the flow rate of the refrigerant discharged from the open hole can be increased, and the pressure in the back pressure chamber can be lowered to increase the differential pressure acting on the valve body. Therefore, the lift amount of the valve body (maximum opening of the throttle device) can be increased, and even if a foreign object is caught between the valve body and the valve port, the opening degree of the throttle device is maximized. In addition, if the refrigeration cycle is controlled, foreign matter can be removed to the secondary chamber side by the flow of refrigerant flowing from the primary chamber to the secondary chamber, preventing the foreign matter from becoming clogged. it can.

It is the longitudinal cross-sectional view of the diaphragm | throttle device of embodiment of this invention, a bottom sectional view, and sectional drawing. It is a schematic block diagram of the refrigerating cycle of embodiment of this invention. It is a figure which shows the modification of the insertion part of the needle valve in embodiment of this invention. It is a longitudinal cross-sectional view of the diaphragm | throttle device of the reference example of this invention.

Next, an embodiment of the diaphragm device of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view (FIG. 1A) of the diaphragm device of the embodiment , and FIG. 2 is a schematic configuration diagram of the refrigeration cycle of the embodiment. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 1C is a cross-sectional view taken along line BB in FIG.

  First, the refrigeration cycle of FIG. 2 will be described. This refrigeration cycle constitutes, for example, an air conditioner, and includes a compressor 100, a condenser 110, the expansion device 10 according to the embodiment, a strainer 20, and an evaporator 120. The refrigerant compressed by the compressor 100 is supplied to the condenser 110, and the refrigerant condensed by the condenser 110 is sent to the expansion device 10 via the strainer 20. The strainer 20 removes foreign matters contained in the refrigerant flowing through the refrigeration cycle, and is, for example, a filter of about 80 mesh to 100 mesh. The expansion device 10 expands and depressurizes the refrigerant and sends it to the evaporator 120 as will be described later. When the refrigeration cycle is configured as an air conditioner, the evaporator 120 cools the room and obtains a cooling function. The refrigerant evaporated in the evaporator 120 is circulated to the compressor 100.

  As shown in FIG. 1, the expansion device 10 includes a main body case 1 made of a metal tube, a metal valve seat member 2, a guide member 3, a needle valve 4 as a “valve element”, a spring receiver 5, and the like. The coil spring 6 as a “spring member” and a stopper member 7 are provided. The valve seat member 2 and the guide member 3 are integrally formed by cutting a metal material or the like.

  The body case 1 has a cylindrical shape centered on the axis L, and constitutes a primary chamber 11 connected to the condenser 110 via the strainer 20 and a secondary chamber 12 connected to the evaporator 120. Yes. The valve seat member 2 is configured by integrating a substantially columnar valve seat portion 2a aligned with the inner surface of the main body case 1 and a cylindrical portion 2b extending downward from the valve seat portion 2a. A caulking groove 2a1 is formed on the entire circumference of the outer peripheral surface of the valve seat portion 2a (the entire circumference around the axis L). By caulking the main body case 1 at the position of the caulking groove 2a1, the valve seat member 2 is formed. (And the guide member 3) are fixed in the main body case 1. As a result, the valve seat member 2 is disposed between the primary chamber 11 and the secondary chamber 12. Further, the valve seat member 2 is formed with a valve port 21 having a cylindrical hole centered on the axis L, and a conduction chamber 22 having a large diameter that conducts from the valve port 21 to the inside of the cylindrical portion 2b. Yes.

  The guide member 3 has a cylindrical shape and is erected in the secondary chamber 12 from the valve seat member 2, and a gap between the guide member 3 and the main body case 1 serves as a main body side channel 13. The guide member 3 has a columnar guide hole 31 centered on the axis L, and an opening hole 32 is formed at a position adjacent to the valve seat member 2 to conduct the guide hole 31 and the outside (secondary chamber 12). ing. Furthermore, an opening hole 33 is formed above the guide member 3 to connect the guide hole 31 and the outside (secondary chamber 12). The inner peripheral surface of the guide hole 31 is a cylindrical guide surface 31a. The cylindrical guide surface 31a is parallel to the axis L.

  The needle valve 4 is formed at the end of the insertion portion 42, the conical needle portion 41 having a substantially flat end surface of the tip portion 41 a, the insertion portion 42 inserted into the guide hole 31 of the guide member 3, and the insertion portion 42. And a boss portion 43. As shown in FIG. 1C, the insertion portion 42 has a substantially hexagonal column cross-sectional shape in a plane orthogonal to the axis L, and between the adjacent side surfaces of the hexagonal column of the insertion portion 42. A narrow surface serves as a guide portion 42a. The guide valve 42 a slides along the cylindrical guide surface 31 a of the guide hole 31, so that the needle valve 4 is guided to move along the axis L. That is, the guide part 42a is in line contact with the cylindrical guide surface 31a by a line parallel to the axis L, and the line contact part between the guide part 42a and the cylindrical guide surface 31a is a sliding contact part S. . A plurality (six in this example) of sliding contact portions S are provided around the axis L.

  Further, a gap surrounded by the side surface of the hexagonal column of the insertion portion 42 and the cylindrical guide surface 31 a of the guide hole 31 is connected to an introduction path 45 that leads from the space on the valve port 21 side to the back pressure chamber 44 behind the needle valve 4. It has become. That is, the distance between the side surface of the insertion portion 42 and the cylindrical guide surface 31a between the adjacent sliding contact portions S is such that the side surface of the insertion portion 42 in the sliding contact portion S (the side surface of the valve needle valve 4) and the cylindrical guide surface. An introduction path 45 that is wider than the distance from 31a is provided. The boss portion 43 is fitted with a blade 43 a that is in sliding contact with the cylindrical guide surface 31 a of the guide hole 31.

  The spring receiver 5 has a substantially cylindrical shape, and a caulking groove 5a is formed on the entire outer circumference (the entire circumference around the axis L). The spring receiver 5 is fixed in the guide member 3 by caulking the guide member 3 at the position of the caulking groove 5a. The coil spring 6 is disposed in a compressed state in the guide hole 31 between the needle valve 4 and the spring receiver 5 via the blade 43a.

  The stopper member 7 has a substantially cylindrical shape. As shown in FIG. 1B, the stopper member 7 has a D-cut surface 71 formed on the side surface of the columnar member. The primary chamber 11 is conducted to the conduction chamber 22 of the valve seat member 2 through a gap with the portion 2b. In addition, the size of the gap between the D-cut surface 71 of the stopper member 7 and the cylindrical portion 2b is set to a sufficient size so that no pressure loss occurs in the flow of the refrigerant flowing from the primary chamber 11. . Further, a caulking groove 7 a is formed on the outer peripheral surface (around the axis L) other than the D-cut surface 71 of the stopper member 7. The stopper member 7 is fixed to the valve seat member 4 by caulking the cylindrical portion 2b of the valve seat member 2 at the position of the caulking groove 7a. In addition, the stopper member 7 may be constituted by a strainer, and may be a squeezing device provided with a strainer.

  In the state of FIG. 1, the distal end portion 41 a of the needle portion 41 of the needle valve 4 protrudes from the valve port 21 toward the primary chamber 11. The end surface of the tip portion 41 a of the needle portion 41 is in contact with the stopper member 7. Even if the end surface of the tip 41a of the needle 41 is in contact with the stopper 7 by setting the position of the stopper 7 in the axis L direction with respect to the valve seat 2a, the needle 41 and the valve port A gap, that is, an “orifice” may be formed between the two.

  With the above configuration, when the high-pressure refrigerant from the condenser 110 flows into the primary chamber 11, the refrigerant in the primary chamber 11 flows from the gap between the stopper member 7 and the cylindrical portion 2 a to the gap (orifice) between the valve port 21 and the needle portion 41. It flows out into the guide hole 31 through. The refrigerant flowing into the guide hole 31 is divided, one flow refrigerant flows from the opening hole 32 of the guide member 3 to the main body side flow path 13, and the other flow refrigerant passes through the introduction path 45 and the back pressure chamber 44. Flow into. The refrigerant in the main body side flow path 13 flows into the secondary chamber 12 as it is, but the refrigerant in the back pressure chamber 44 flows out into the secondary chamber 12 through the open hole 33 above the guide member 3.

  Since the introduction path 45 surrounded by the needle valve 4 and the cylindrical guide surface 31a has a large cross-sectional area, the flow rate of the refrigerant can be increased. For this reason, the foreign matter mixed in the refrigerant is guided to the introduction path 45 and flows. That is, the clearance in the introduction path 45 is set larger than the clearance (opening) in the strainer 20 of the refrigeration cycle. Therefore, the possibility that foreign matter is caught between the guide portion 42a on the side surface of the needle valve 4 and the cylindrical guide surface 31a of the guide member 3 (clearance) can be minimized. Therefore, the needle valve 4 is not locked by the foreign matter.

  As described above, in the embodiment, in the needle valve 4 having the plurality of guide portions 42a, a plurality of sliding contact portions S are provided around the axis L by the guide portions 42a and the cylindrical guide surface 31a. In the sliding contact portion S, the guide portion 42a and the cylindrical guide surface 31a are in line contact. The distance between the side surface of the insertion portion 42 and the cylindrical guide surface 31a between the adjacent sliding contact portions S is such that the side surface of the insertion portion 42 (side surface of the valve needle valve 4) in the sliding contact portion S and the cylindrical guide surface. The introduction path 45 is wider than the distance from 31a. And the total area of the cross section in the surface orthogonal to the axis L of the introduction path 45 provided in the side surface (side surface of the insertion part 42) of the needle valve 4 is smaller than the area of the open hole 33. Therefore, since the total area of the introduction path 45 is smaller than the area of the open hole 33, the refrigerant passing through the valve port 21 is throttled by the side surface of the needle portion 41, so that the refrigerant flowing into the back pressure chamber 44 The flow rate of the refrigerant discharged from the open hole 33 can be increased with respect to the flow rate. Therefore, the pressure in the back pressure chamber 44 can be reduced, the differential pressure acting on the needle valve 4 can be increased, and the lift amount of the needle valve 4 (maximum opening of the expansion device 10) is increased. be able to. Therefore, even if a foreign object is caught between the needle portion 41 and the valve port 21, the refrigeration cycle is controlled so that the opening degree of the expansion device 10 is maximized, for example, by increasing the rotational speed of the compressor 100. If it does, the foreign material pinched | interposed between the needle part 41 and the valve port 21 with the flow of the refrigerant | coolant which flows out out of the primary chamber 11 to the secondary chamber 12 can be removed to the secondary chamber side. Thereby, it can prevent that the foreign material will be in the state where it was clogged between the needle part 41 and the valve port 21. FIG.

  Note that hunting of the needle valve 4 (vibration in the direction of the axis L of the needle valve 4) can be prevented by the sliding resistance between the blade 43a and the cylindrical guide surface 31a. That is, when the valve starts to open, the primary pressure rapidly decreases. Therefore, the needle valve 4 is displaced in the valve closing direction. However, when the needle valve 4 is displaced in the valve closing direction, the primary pressure acting on the needle valve 4 is increased, and the needle valve 4 is again displaced in the valve opening direction. To do. Although this repetition is hunting, the sliding resistance by the blades 43a can suppress the needle valve 4 from following the fluctuation of the differential pressure, and the hunting can be prevented. When the valve opening degree is large, the flow rate of the refrigerant in the guide hole 31 is also large. Therefore, the refrigerant pressure of the refrigerant acts in the direction separating the blades 43a from the cylindrical guide surface 31a, so that the sliding resistance is also small. Thus, the hysteresis of the differential pressure-opening characteristic can be reduced.

  FIG. 3 is a view showing a modified example of the insertion portion 42 of the needle valve 4 and corresponds to a cross-sectional view taken along the line BB of FIG. 1 (FIG. 1C). Elements corresponding to those in FIG. 1 are denoted by the same reference numerals as those in FIG. The insertion portion 46 of the needle valve 4 in FIG. 3A is an example of a quadrangular prism shape, and the corner of the quadrangular prism is a guide portion 46a that slides along the cylindrical guide surface 31a. The guide portion 46a is in line contact with the cylindrical guide surface 31a by a line parallel to the axis L, and a portion of the guide portion 46a and the cylindrical guide surface 31a in line contact is a slidable contact portion S. . A plurality (four in this example) of the sliding contact portions S are provided around the axis L. The distance between the side surface of the insertion portion 46 and the cylindrical guide surface 31a between the adjacent sliding contact portions S is such that the side surface of the insertion portion 46 in the sliding contact portion S (the side surface of the valve needle valve 4) and the cylindrical guide surface. The introduction path 45 is wider than the distance from 31a. In this example, the cross-sectional area of the introduction path 45 is larger than that of the hexagonal column in FIG. Thereby, the flow rate of the refrigerant flowing through the introduction path 45 is further increased, and the possibility that foreign matter is caught between the guide portion 46a and the cylindrical guide surface 31a can be further reduced.

  The insertion part 47 of the needle valve 4 in FIG. 3B has three arc-shaped ridges formed on the side surface, and the guide part in which the protruding end of the arc-shaped ridge slides along the cylindrical guide surface 31a. 47a. Also in this example, the guide portion 47a is in line contact with the cylindrical guide surface 31a by a line parallel to the axis L, and a portion where the guide portion 47a and the cylindrical guide surface 31a are in line contact becomes the sliding contact portion S. ing. A plurality (three in this example) of sliding contact portions S are provided around the axis L. Further, the distance between the side surface of the insertion portion 47 and the cylindrical guide surface 31a between the adjacent sliding contact portions S is such that the side surface of the insertion portion 47 in the sliding contact portion S (side surface of the valve needle valve 4) and the cylindrical guide surface. The introduction path 45 is wider than the distance from 31a. In this example as well, the possibility of foreign matter being caught between the guide portion 47a and the cylindrical guide surface 31a due to the flow rate of the refrigerant flowing through the introduction path 45 can be further reduced.

FIG. 4 is a longitudinal sectional view of a diaphragm device according to a reference example . Elements similar to those in the embodiment are denoted by the same reference numerals as in FIGS. The expansion device 10 of the reference example is also provided in the refrigeration cycle of FIG. 2 as in the embodiment .

The throttle device 10 of this reference example is configured to guide the needle valve 4 with the main body case 1 instead of the guide member 3 of the embodiment . As shown in FIG. 4, the throttle device 10 of this reference example includes a main body case 1 made of a metal tube, a metal valve seat member 2, a needle valve 4 as a “valve element”, an adjustment screw 81, A coil spring 6 as a “spring member” and a stopper member 82 are provided.

  The body case 1 has a cylindrical shape centered on the axis L, and constitutes a primary chamber 11 connected to the condenser 110 via the strainer 20 and a secondary chamber 12 connected to the evaporator 120. Yes. The inner peripheral surface of the main body case 1 is a cylindrical guide surface 1a. The cylindrical guide surface 1a is parallel to the axis L.

  The valve seat member 2 has a substantially cylindrical shape that matches the inner surface of the main body case 1. A caulking groove 2a1 is formed on the entire outer circumference of the valve seat member 2 (the entire circumference around the axis L). By caulking the main body case 1 at the position of the caulking groove 2a1, the valve seat member 2 is formed. Is fixed in the main body case 1. As a result, the valve seat member 2 is disposed between the primary chamber 11 and the secondary chamber 12.

  The valve seat member 2 is formed with a valve port 21 having a cylindrical hole centered on the axis L, and a screw hole 23 that opens coaxially with the valve seat member 2 from the valve port 21 to the primary chamber 11 side. Is formed. A female screw portion 23 a is formed on the inner periphery of the screw hole 23. The stopper member 82 has a cylindrical shape, and a male screw portion 82a is formed on the outer periphery thereof. The stopper member 82 is formed with three conduction holes 82b around the axis L. The stopper member 82 is attached to the valve seat member 2 by screwing the male screw portion 82 a on the outer periphery thereof with the female screw portion 23 a of the screw hole 23 of the valve seat member 2.

  A female screw member 83 having a female screw portion 83a on the inner side is disposed above the inside of the main body case 1. A caulking groove 2a1 is formed on the entire circumference of the outer peripheral surface of the female screw member 83 (the entire circumference around the axis L). By caulking the main body case 1 at the position of the caulking groove 2a1, the female screw member 83 becomes a main body. It is fixed in the case 1. The adjustment screw 81 has a male screw portion 81a formed on the outer periphery thereof, and a slit 81b for fitting a minus driver to the end portion on the secondary chamber 12 side. Further, the adjustment screw 81 is formed with a through hole 81c passing through the center thereof. The coil spring 6 is disposed in a compressed state between the needle valve 4 and the adjusting screw 81 via the blades 43 a in the main body case 1. The adjusting screw 81 is attached to the female screw member 83 by screwing the male screw portion 81a on the outer periphery thereof with the female screw portion 83a of the female screw member 83. As a result, the coil spring 6 biases the needle valve 4 toward the primary chamber 11, and the biasing force that biases the needle valve 4 is adjusted by the screwing amount of the adjustment screw 81 into the female screw member 83.

The needle valve 4 in this reference example is formed at a conical needle portion 41 similar to the embodiment , an insertion portion 48 inserted into the cylindrical guide surface 1a of the main body case 1, and an end portion of the insertion portion 48. And a boss portion 43. The insertion portion 48 has a quadrangular prism shape similar to the insertion portion of FIG. 3A described above, and a narrow surface between adjacent side surfaces of the quadrangular column of the insertion portion 48 is a guide portion. 48a.

Then, the needle valve 4 is guided to move along the axis L as the guide portion 48 a slides along the cylindrical guide surface 1 a of the main body case 1. That is, the guide portion 48a and the cylindrical guide surface 1a are in line contact, and the portion in line contact is a “sliding contact portion”. A space surrounded by the side surface of the quadrangular column of the insertion portion 48 and the cylindrical guide surface 1 a is an introduction path 45 that leads from the space on the valve port 21 side to the back pressure chamber 44. Also in this reference example , since the cross-sectional area of the introduction path 45 is widened, the flow rate of the refrigerant flowing through the introduction path 45 is further increased, and there is a possibility that foreign matter is caught between the guide portion 48a and the cylindrical guide surface 1a. It can be made even smaller.

In this reference example , the position of the distal end portion 41a of the needle portion 41 (the position of the end portion on the primary chamber side of the valve body) is positioned by the stopper member 82. The flow rate of the refrigerant flowing through the orifice, that is, the bleed flow rate can be adjusted by the screwing amount of the stopper member 82 into the valve seat member 2. Thus, since it can be adjusted by the screwing amount, the bleed flow rate can be adjusted with extremely high accuracy. After the position of the stopper member 82 is adjusted, the stopper member 82 is fixed to the valve seat member 2 by, for example, adhesion, brazing, caulking, or the like.

  In the above embodiment, the case where the guide portion on the needle valve side and the cylindrical guide surface are in line contact with each other in the direction parallel to the axis L in the sliding contact portion S has been described. The present invention can also be applied to the case of contact.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention. The example in which the guide surface that guides the needle valve is cylindrical has been described. For example, the guide surface has a prismatic shape parallel to the axis, and the cylindrical insertion portion of the needle portion is inserted inside the guide surface. The outer periphery may be guided by a prismatic guide surface.

DESCRIPTION OF SYMBOLS 1 Main body case 11 Primary chamber 12 Secondary chamber 2 Valve seat member 3 Guide member 31a Cylindrical guide surface 33 Open hole 4 Needle valve (valve body)
41 Needle part 42 Insertion part 42a Guide part 44 Back pressure chamber 45 Introduction path 46 Insertion part 46a Guide part 47 Insertion part 47a Guide part 48 Insertion part 48a Guide part 6 Coil spring (spring member)
7 Stopper member S Sliding part

Claims (3)

A throttling device that is provided between a condenser and an evaporator of a refrigeration cycle, decompresses the refrigerant condensed by the condenser, and sends the refrigerant to the evaporator,
A main body case constituting a primary chamber connected to the condenser and a secondary chamber connected to the evaporator;
A valve seat member formed between the primary chamber and the secondary chamber in the main body case in which a valve port is formed;
A valve body that varies the opening of the valve port by moving along the axis of the valve port ;
A spring member for urging the valve body toward the valve port;
A cylindrical guide member that is coaxial with the valve port and is disposed on the secondary chamber side in the main body case, the valve body is inserted, and a cylindrical guide surface parallel to the axis is formed inside. ,
With
With the sliding contact portion is a point contact or a portion in line contact, between the side surface and the cylindrical guide surface of the valve body is provided with a plurality around said axis, of the valve body between adjacent sliding contact portion with spacing between the side and the cylindrical guide surface is provided as an introduction passage for flowing the coolant is wider than the distance between the side surface and the cylindrical guide surface of the valve body in the sliding contact portion, and the introduction path A throttling device comprising an open hole formed between the valve seat member and conducting between the inside and the outside of the guide member . The guide member is formed with a second opening hole for releasing the refrigerant from the back pressure chamber behind the valve body to the secondary chamber side, and the total cross section in a plane perpendicular to the axis of the introduction path 2. A diaphragm according to claim 1 , wherein the area is smaller than the area of the second open hole. A refrigerating cycle, wherein the expansion device according to claim 1 or 2 is provided between a condenser and an evaporator.

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