CN113574303B

CN113574303B - Expansion valve

Info

Publication number: CN113574303B
Application number: CN202080020698.7A
Authority: CN
Inventors: 富塚真弘; 横田浩; 矢野卓宏
Original assignee: Fujikoki Corp
Current assignee: Fujikoki Corp
Priority date: 2019-03-15
Filing date: 2020-02-10
Publication date: 2024-01-23
Anticipated expiration: 2040-02-10
Also published as: JP7089769B2; CN113574303A; EP3940279A1; WO2020189092A1; US20220146160A1; JP2020148305A; EP3940279A4

Abstract

The present invention provides an improved expansion valve having a simple structure and capable of reducing noise. The expansion valve (10) has: a valve body (2) provided with a valve chamber (VS) and a valve seat (20); a valve element (3) that is seated on the valve seat to prevent passage of fluid, and that is separated from the valve seat to allow passage of the fluid; a coil spring (41) that biases the valve element toward the valve seat; and a working rod (5) which presses the valve body in a direction to separate the valve body from the valve seat against a force applied by the coil spring, wherein the valve chamber (VS) has a cylindrical inner wall (24) connected to the valve seat, the valve body (3) has a contact portion (31) seated on the valve seat and a cylindrical body portion (32) facing the inner wall, and the body portion has a connection surface (32 b) slidable with respect to the inner wall and a plane (32 a) having a gap between the body portion and the inner wall.

Description

Expansion valve

Technical Field

The present invention relates to an expansion valve.

Background

Conventionally, in a refrigeration cycle system used in an air conditioner or the like mounted in an automobile, a temperature-sensitive expansion valve that adjusts the throughput of refrigerant according to the temperature is used in order to omit installation space and piping.

In a general expansion valve, a spherical valve body disposed in a valve chamber is disposed so as to face a valve seat that opens into the valve chamber. The valve body is supported by a valve body support disposed in the valve chamber, and is biased in the valve seat direction by a coil spring provided between a spring receiving member attached to the valve body and the valve body support. The valve body is pushed by the operating rod driven by the power element, and is separated from the valve seat, so that the refrigerant can pass through. The refrigerant passing through the throttle flow path between the valve seat and the valve element is sent from the outlet port to the evaporator side.

However, at the start of the refrigeration cycle, the liquid density of the refrigerant passing through the throttle passage between the valve seat and the valve element is low, and the flow rate of the refrigerant increases as the flow resistance decreases. Therefore, at the start-up, friction sound in the valve portion tends to increase, and as a countermeasure for this, flow rate limitation of the refrigerant is required. On the other hand, in the stationary phase of the elapsed time from the start-up of the refrigeration cycle, the liquid density becomes higher than that at the start-up of the refrigeration cycle, and therefore the friction sound becomes smaller. Therefore, there is no need for excessive flow restriction during the stationary phase, but rather there is a reverse requirement that it is desirable to ensure a sufficient refrigerant flow.

In contrast, patent document 1 discloses an expansion valve in which a clearance between a valve body support and a valve chamber and a refrigerant inlet to the valve chamber are defined so that the friction sound of the refrigerant at the time of starting the refrigeration cycle is reduced and the necessary flow rate of the refrigerant passing through a throttle passage is ensured in a well-balanced manner.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5369259

Technical problem to be solved by the invention

On the other hand, in the expansion valve, noise other than the friction sound of the refrigerant is also generated. For example, in the expansion valve disclosed in patent document 1, bubbles in the refrigerant reach a valve seat in an unbroken state, and when the refrigerant passes through the valve seat, the bubbles break at the same time, and sometimes become known as noise.

Disclosure of Invention

It is therefore an object of the present invention to provide an improved expansion valve having a simple structure and capable of reducing noise.

Technical means for solving the technical problems

In order to achieve the above object, an expansion valve of the present invention includes: a valve body having a valve chamber and a valve seat; a valve element that is seated on the valve seat to restrict passage of fluid, and that is separated from the valve seat to allow passage of fluid; a coil spring that biases the valve element toward the valve seat; and a working rod that presses the valve body in a direction to separate the valve body from the valve seat against a biasing force applied by the coil spring, wherein the valve chamber has a tubular inner wall connected to the valve seat, the valve body has a contact portion that is seated on the valve seat, and a tubular body portion that faces the inner wall, and when a cross section is taken in a direction orthogonal to an axis of the valve body, a shape of an inner periphery of the inner wall is made different from a shape of an outer periphery of the body portion, so that a space through which the fluid passes is formed between the inner wall and the body portion, and the inner periphery of the inner wall is partially slidably contacted with the outer periphery of the body portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an improved expansion valve having a simple structure and capable of reducing noise can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view schematically showing an example in which the expansion valve according to the first embodiment is applied to a refrigerant cycle system.

Fig. 2 is a top view of a cross section at line A-A of fig. 1.

Fig. 3 is a perspective view of the valve body according to the present embodiment.

Fig. 4 is an enlarged sectional view showing the vicinity of the valve element of the expansion valve according to the second embodiment.

Fig. 5 is a top view of a cross section at line B-B of fig. 4.

Fig. 6 is a perspective view of the valve body according to the present embodiment.

Fig. 7 is an enlarged sectional view showing the vicinity of the valve element of the expansion valve according to the third embodiment.

Fig. 8 is a top view of the cross section at line C-C of fig. 7.

Fig. 9 is a perspective view of the valve body of the present embodiment.

Fig. 10 is a cross-sectional view of a main body portion of a modification.

Detailed Description

(definition)

In the present specification, the direction from the valve body 3 toward the working rod 5 is defined as "upward direction", and the direction from the working rod 5 toward the valve body 3 is defined as "downward direction". Therefore, in the present specification, the direction from the valve body 3 toward the operation rod 5 is referred to as "upward direction" regardless of the posture of the expansion valve 10.

In the present specification, the "polygonal tubular shape" refers to a tubular shape having an outer periphery surrounding an axis with four or more planes. However, when there is a connection surface connecting the planes to each other, it is assumed that the connection surface is not included in the planes. In addition, "the shape of the inner periphery in the cross section is different from the shape of the outer periphery" means that the shape of the inner periphery is neither the same nor similar to the shape of the outer periphery.

(first embodiment)

An outline of the expansion valve 10 according to the first embodiment will be described with reference to fig. 1. Fig. 1 is a schematic cross-sectional view schematically showing an example in which the expansion valve 10 according to the present embodiment is applied to a refrigerant cycle system 100. In the present embodiment, the expansion valve 10 is connected to the compressor 101, the condenser 102, and the evaporator 104, and thus the refrigerant cycle system 100 is configured.

The expansion valve 10 includes: a valve body 2 having a cylindrical valve chamber VS, a valve body 3, a biasing device 4, an operating rod 5, and an annular spring 6.

The valve body 2 includes a first flow path 21 and a second flow path 22 in addition to the valve chamber VS. The first flow path 21 is, for example, a supply-side flow path, and supplies a refrigerant (also referred to as fluid) to the valve chamber VS via the supply-side flow path. The second flow path 22 is, for example, a discharge-side flow path, and the fluid in the valve chamber VS is discharged to the outside of the expansion valve through the orifice portion 27 and the second flow path 22. The first flow path 21 and the valve chamber VS are connected by a connection path 21a having a smaller diameter than the first flow path 21.

The valve chamber VS includes a valve seat 20 and a cylindrical inner wall 24 connected to the valve seat 20 and having a larger diameter than the valve seat 20, and the valve seat 20 has a lower edge inner periphery of a cylindrical orifice portion 27.

Fig. 2 is a top view of a cross section taken along line A-A of fig. 1, showing a cross section taken in a direction orthogonal to the axis of the valve body 3. Fig. 3 is a perspective view of the valve element 3. In fig. 3, the valve body 3 is formed by connecting a conical contact portion 31, a hexagonal cylindrical body portion 32, a circular plate-shaped flange portion 33, and a cylindrical end portion 34.

The tapered surface 31b of the contact portion 31 contacts the valve seat 20. The upper surface 31a of the abutting portion 31 is a plane orthogonal to the axis L. The outer periphery of the main body portion 32 is formed by six flat surfaces 32a and a connecting surface 32b formed between adjacent flat surfaces 32 a. The connecting surface 32b may be a flat surface or a curved surface, but preferably has a circumference of 1/4 or less of the circumference of the flat surface 32 a. The axial length of the body 32 is preferably equal to or more than the diameter of the inner wall 24 of the valve chamber VS (or the maximum diagonal length of the body 32).

The valve body 3 is disposed in the valve chamber VS. In the cross section of fig. 2, the inner peripheral shape of the inner wall 24 of the valve chamber VS is different from the outer peripheral shape of the main body portion 32, and the inner wall 24 of the valve chamber VS is brought into contact with and slides against any one of the joint surfaces 32b according to the eccentricity of the valve chamber VS and the valve body 3. On the other hand, the inner wall 24 of the valve chamber VS is not in contact with the flat surface 32a, regardless of the eccentricity of the valve chamber VS and the valve body 3. Thus, the refrigerant passes through the space between the inner wall 24 and the plane 32 a.

In fig. 1, when the valve body 3 is seated on the annular valve seat 20 of the valve body 2, the first flow path 21 and the second flow path 22 are in a non-communication state. On the other hand, when the valve body 3 is separated from the valve seat 20, the first flow path 21 and the second flow path 22 are in communication. However, when the valve body 3 is seated on the valve seat 20, a limited amount of refrigerant may pass through.

The lower end of the operating rod 5 inserted through the orifice portion 27 through the operating rod insertion hole 28 of the valve body 2 is in contact with the upper surface 31a of the valve body 3 so as to be relatively displaceable in a direction intersecting the axis L. The operating rod 5 can press the valve body 3 in the valve opening direction against the biasing force applied by the biasing means 4. When the operation rod 5 moves downward, the valve body 3 is separated from the valve seat 20, and the expansion valve 10 is opened.

Next, the power element 8 that drives the work bar 5 will be described. In fig. 1, the power element 8 is mounted to a recess 2a provided at the top of the valve body 2. The concave portion 2a communicates with a return flow path 23 in the valve body 2 through which the refrigerant from the evaporator 104 passes through via a communication path 2b. The working rod 5 passes through the communication path 2b. A female screw is formed on the inner periphery of the recess 2a.

The power element 8 has a plug 81, an upper cover member 82, a diaphragm 83, a stopper member 84, and a receiving member 86.

The upper cover member 82 includes a central conical portion 82a and an annular flange portion 82b extending from the lower end of the conical portion 82a to the outer periphery. An opening 82c is formed at the top of the conical portion 82a, and can be sealed by the plug 81.

The diaphragm 83 is formed of a thin plate material having a concave-convex shape formed with a plurality of concentric circles, and has an outer diameter substantially equal to that of the flange 82b.

The stopper member 84 has a fitting hole 84a in the center of the lower end.

The receiving member 86 has: a flange portion 86a having an outer diameter substantially equal to an outer diameter of the flange portion 82b of the upper cover member 82, a stepped portion 86c having an annular support surface 86b substantially orthogonal to the axis L, and a hollow cylindrical portion 86d. An external thread is formed on the outer periphery of the hollow cylindrical portion 86d.

The assembly sequence of the power element 8 will be described. The upper cover member 82, the diaphragm 83, the stopper member 84, and the receiving member 86 are disposed so as to be in a positional relationship as shown in fig. 1.

In a state where the outer peripheral portions of the flange 82b of the upper cover member 82, the diaphragm 83, and the flange 86a of the receiving member 86 are overlapped, the outer peripheral portions are integrally formed by peripheral welding, such as TIG welding, laser welding, or plasma welding.

Next, after the working gas is sealed from the opening 82c formed in the upper cover member 82 into the space (pressure working chamber PO) surrounded by the upper cover member 82 and the diaphragm 83, the opening 82c is sealed with the plug 81, and the plug 81 is fixed to the upper cover member 82 by projection welding or the like.

At this time, the diaphragm 83 receives pressure by the working gas sealed in the pressure working chamber PO so as to protrude toward the receiving member 86, and is supported by being in contact with the upper surface of the stopper member 84 disposed in the space (pressure detection chamber PD) surrounded by the diaphragm 83 and the receiving member 86.

In assembling the power element 8, the male screw of the hollow cylindrical portion 86d of the receiving member 86 and the female screw of the recess 2a of the valve body 2 communicating with the return flow path 23 are screwed together in a state in which the upper end of the operating rod 5 is fitted into the fitting hole 84a of the stopper member 84, whereby the power element 8 is fixed to the valve body 2.

At this time, the seal PK is interposed between the power element 8 and the valve body 2, and refrigerant is prevented from leaking from the concave portion 2a when the power element 8 is attached to the valve body 2. In this state, the pressure detection chamber PD of the power element 8 communicates with the return flow path 23.

The annular spring 6 is a vibration isolation member that suppresses vibration of the work bar 5. The annular spring 6 is disposed in the annular portion 26 adjacent to the rod insertion hole 28 of the valve body 2, and applies a predetermined elastic force to the outer peripheral surface of the rod 5 by a claw portion protruding toward the inner peripheral side.

The biasing device 4 includes a coil spring 41 formed by winding a circular wire into a coil shape, and a spring receiving member 43. The spring receiving member 43 has a function of sealing the opening of the valve chamber VS of the valve body 2 and a function of supporting the lower end of the coil spring 41. An O-ring 44 is disposed between the spring receiving member 43 and the inner wall of the valve chamber VS to prevent leakage of the refrigerant.

The upper end of the coil spring 41 is brought into contact with the lower surface of the flange portion 33 of the valve body 3, and the end 34 of the valve body 3 is fitted inside the upper end of the coil spring 41, thereby holding the valve body 3 shown in fig. 3.

(action of expansion valve)

An example of the operation of the expansion valve 10 will be described with reference to fig. 1. The refrigerant pressurized in the compressor 101 is liquefied in the condenser 102 and sent to the expansion valve 10. The refrigerant adiabatically expanded in the expansion valve 10 is sent to the evaporator 104, and the refrigerant exchanges heat with air flowing around the evaporator 104. The refrigerant returned from the evaporator 104 passes through the expansion valve 10 (more specifically, the return flow path 23) and returns to the compressor 101.

The high-pressure refrigerant is supplied from the condenser 102 to the expansion valve 10. More specifically, the high-pressure refrigerant from the condenser 102 is supplied to the valve chamber VS via the first flow path 21.

When the contact portion 31 of the valve body 3 is seated on the valve seat 20 (in other words, when the expansion valve 10 is in the closed state), the first flow path 21 on the upstream side of the valve chamber VS and the second flow path 22 on the downstream side of the valve chamber VS are in a non-communication state. On the other hand, when the contact portion 31 of the valve body 3 is separated from the valve seat 20 (in other words, when the expansion valve 10 is in the open state), the refrigerant supplied to the valve chamber VS is sent to the evaporator 104 through the orifice portion 27 and the second flow path 22.

According to the present embodiment, when the abutment portion 31 of the valve body 3 is separated from the valve seat 20, the bubble-containing refrigerant in the valve chamber VS gradually breaks while passing through the relatively narrow gap between the flat surface 32a of the body portion 32 and the inner wall 24 throughout the axial length of the body portion 32 of the valve body 3. Therefore, the bubbles are not broken at the same time when the refrigerant passes through the valve seat 20, and the energy at the time of bubble breaking can be reduced to reduce the pass sound. In addition, the rectification effect of the refrigerant is obtained by flowing the refrigerant along the plane 32a extending over the axial length of the main body 32.

The switching between the closed state and the open state of the expansion valve 10 is performed by the operating rod 5 connected to the power element 8. At this time, the connecting surface 32b of the main body 32 in sliding contact with the inner wall 24 has a long span corresponding to the axial length of the main body 32, so that the inclination generated when the abutment portion 31 of the valve body 3 is separated from the valve seat 20 can be suppressed. Therefore, the smooth operation of the valve body 3 can be ensured in cooperation with the relative displacement of the upper surface 31a and the working rod 5.

In fig. 1, a pressure operating chamber PO and a pressure detecting chamber PD partitioned by a diaphragm 83 are provided inside the power element 8. Therefore, if the working gas in the pressure working chamber PO is liquefied, the working rod 5 moves upward, and if the liquefied working gas is gasified, the working rod 5 moves downward. In this way, the switching between the open state and the closed state of the expansion valve 10 is performed.

The pressure detection chamber PD of the power element 8 communicates with the return flow path 23. Therefore, the pressure of the refrigerant flowing in the return flow path 23 is transmitted to the working gas in the pressure working chamber PO via the stopper 84 and the diaphragm 83. Thereby, the volume of the working gas in the pressure working chamber PO changes, and the working rod 5 is driven. In other words, in the expansion valve 10 shown in fig. 1, the amount of the refrigerant supplied from the expansion valve 10 to the evaporator 104 is automatically adjusted according to the pressure of the refrigerant returned from the evaporator 104 to the expansion valve 10.

(second embodiment)

Next, an expansion valve according to a second embodiment will be described. Fig. 4 is an enlarged sectional view showing the vicinity of the valve element of the expansion valve 10A. Fig. 5 is a top view of a cross section at line B-B of fig. 4. Fig. 6 is a perspective view of the valve body 3A.

In fig. 6, the valve body 3A is formed by connecting a conical contact portion 31A, a hexagonal cylindrical body portion 32A, and a cylindrical end portion 34A.

The tapered surface 31Ab of the contact portion 31A contacts the valve seat 20. The upper surface 31Aa of the abutting portion 31A is a plane orthogonal to the axis L. The outer periphery of the main body portion 32A is formed by six planes 32Aa and a connecting surface 32Ab formed between adjacent planes 32 Aa. The connecting surface 32Ab may be a plane surface or a curved surface. The length of the main body portion 32A is preferably equal to or more than the diameter of the inner wall 24A of the valve chamber VS (or the maximum length of the diagonal line of the main body portion 32A). The connecting surface 32Ab constitutes a sliding contact portion, and the flat surface 32Aa constitutes a flow path portion.

The inner wall 24A of the valve chamber VS is larger than the outer diameter of the coil spring 41. Other structures are the same as those of the above-described embodiment, and therefore the same reference numerals are given thereto, and repetitive description thereof will be omitted.

According to the present embodiment, when the abutting portion 31A of the valve body 3A is separated from the valve seat 20, the bubble is gradually broken while the refrigerant containing the bubble in the valve chamber VS passes through the relatively narrow gap between the plane 32Aa of the body portion 32A and the inner wall 24A throughout the axial length of the body portion 32A of the valve body 3A. Therefore, the bubbles are not broken at the same time when the refrigerant passes through the valve seat 20, and the energy at the time of bubble breaking can be reduced to reduce the pass sound. In addition, the refrigerant flows along the plane 32Aa extending along the axial length of the main body 32A, thereby obtaining the refrigerant rectifying effect.

Since the connecting surface 32Ab of the body portion 32A that abuts against the inner wall 24A has a long span corresponding to the axial length of the body portion 32A when the valve is opened and closed, the inclination generated when the abutment portion 31A of the valve body 3A is separated from the valve seat 20 can be suppressed. Therefore, the smooth operation of the valve body 3A can be ensured in cooperation with the upper surface 31Aa being able to relatively displace with the working rod 5.

In particular, since the contact position of the connecting surface 32Ab with the inner wall 24A is relatively far from the axis L, the inclination of the valve body 3A can be effectively suppressed.

(third embodiment)

Next, an expansion valve according to a third embodiment will be described. Fig. 7 is an enlarged sectional view showing the vicinity of the valve element of the expansion valve 10B. Fig. 8 is a top view of the cross section at line C-C of fig. 7. Fig. 9 is a perspective view of the valve body 3B.

In fig. 9, the valve body 3B is formed by connecting a conical contact portion 31B, a cylindrical body portion 32B, a disk-shaped flange portion 33B, and a cylindrical end portion 34B.

The tapered surface 31Bb of the contact portion 31B contacts the valve seat 20. The upper surface 31Ba of the abutting portion 31B is a plane orthogonal to the axis L. The length of the body portion 32B is preferably equal to or more than the maximum diagonal length of the inner wall 24B of the valve chamber VS (or the diameter of the body portion 32B).

As shown in fig. 8, the inner wall 24B of the valve chamber VS has a hexagonal cylindrical shape formed by six flat surfaces 24 Bb. The outer periphery of the body portion 32B of the valve body 3B is in contact with the flat surface 24Bb at any one of six tangential points CP shown in fig. 8. Therefore, the tangential points CP on the outer peripheral surface of the body portion 32B constitute a sliding contact portion, and the outer peripheral surfaces between adjacent tangential points CP constitute a flow path portion. Other structures are the same as those of the above-described embodiment, and therefore the same reference numerals are given thereto, and repetitive description thereof will be omitted.

According to the present embodiment, when the contact portion 31B of the valve body 3B is separated from the valve seat 20, the bubble is gradually broken while the bubble-containing refrigerant in the valve chamber VS passes through the relatively narrow gap between the outer peripheral surface of the body portion 32B and the inner wall 24B over the axial length of the body portion 32B of the valve body 3B. Therefore, the bubbles are not broken at the same time when the refrigerant passes through the valve seat 20, and the energy at the time of bubble breaking can be reduced to reduce the pass sound. In addition, the rectification effect of the refrigerant is obtained by flowing the refrigerant over the plane 24Bb along the axial length of the main body portion 32B.

The flat surface 24Bb abutting against the body portion 32B has a long span in the axial direction of the valve body 3B when the valve is opened and closed, and therefore, inclination occurring when the abutting portion 31B of the valve body 3B is separated from the valve seat 20 can be suppressed. Therefore, the smooth operation of the valve body 3B can be ensured in cooperation with the relative displacement of the upper surface 31Ba and the operating rod 5.

(modification)

Fig. 10 is a view similar to fig. 2 showing a cross section of the valve body and the inner wall of the valve chamber according to the modification. In the present modification, the valve body 32D has a non-circular cross section with respect to the inner wall 24D of the valve chamber in the valve body 2D. Specifically, the body portion 32D is formed of a partial cylindrical surface 32Da and a flat surface 32 Db. The width of the flat surface 32Db is shorter than the diameter of the partial cylindrical surface 32 Da. The cross-sectional shape of the main body portion 32D is the same over the entire length of the main body portion 32D. The partial cylindrical surface 32Da constitutes a sliding contact portion, and the flat surface 32Db constitutes a flow path portion. Other structures are the same as those of the above-described embodiment, and therefore the same reference numerals are given thereto, and repetitive description thereof will be omitted.

According to this modification, when the valve body is separated from the valve seat, the bubble gradually breaks while the refrigerant containing the bubble in the valve body passes through the relatively narrow gap between the flat surface 32Db of the body 32D and the inner wall 24D throughout the axial length of the body 32D of the valve body. Therefore, the bubbles are not broken at the same time when the refrigerant passes through the valve seat, and the energy at the time of bubble breaking can be reduced to reduce the pass sound. In addition, the rectification effect of the refrigerant is obtained by flowing the refrigerant along the plane 32Db extending over the axial length of the main body portion 32D.

The present invention is not limited to the above-described embodiments. Any modification of the components of the above embodiments can be performed within the scope of the present invention. In the above embodiment, any component may be added or omitted. For example, the flow path portion is not limited to a flat surface, and may be a convex curved surface or a concave curved surface.

Symbol description

10. 10A, 10B expansion valve

2. 2A, 2B, 2D valve body

3. 3A, 3B valve core

4 force application device

5 working rod

6 annular spring

8 power element

20 valve seat

21 first flow path

22 second flow path

23 return flow path

26 ring-shaped part

27 orifice portion

41 coil spring

42 spool support

43 spring receiving member

100 refrigerant circulation system

101 compressor

102 condenser

104 evaporator

VS valve chamber

Claims

1. An expansion valve, comprising:

a valve body having a valve chamber and a valve seat;

a valve element that is seated on the valve seat to restrict passage of fluid, and that is separated from the valve seat to allow passage of fluid;

a coil spring that biases the valve element toward the valve seat; and

a working rod that presses the valve element in a direction to separate the valve element from the valve seat against a biasing force exerted by the coil spring,

the valve chamber has a cylindrical inner wall connected to the valve seat,

the valve body has a cylindrical main body portion which is seated on the contact portion of the valve seat and faces the inner wall,

when the valve body is formed with a cross section in a direction perpendicular to the axis of the valve body, a space through which the fluid passes is formed between the inner wall and the main body by making the shape of the inner periphery of the inner wall different from the shape of the outer periphery of the main body, the inner periphery of the inner wall and the outer periphery of the main body are partially slidably contacted,

a connection path for introducing fluid into the valve chamber is formed in a portion of the valve chamber opposite to the valve seat with respect to the inner wall opposite to the main body portion,

during passage of the fluid through the space formed between the inner wall and the body portion, the bubbles of the fluid collapse,

the fluid passes through the valve seat after passing through the space formed between the inner wall and the body portion,

the length of the main body in the axial direction is equal to or more than the diameter of the inner wall, equal to or more than the maximum diagonal length of the main body, equal to or more than the maximum diagonal length of the inner wall, or equal to or more than the diameter of the main body.

2. The expansion valve of claim 1, wherein the valve is configured to,

the inner wall has a cylindrical shape, and the main body portion has a polygonal cylindrical shape.

3. The expansion valve of claim 1, wherein the valve is configured to,

the inner wall has a polygonal tubular shape, and the main body portion has a tubular shape.

4. The expansion valve of claim 1, wherein the valve is configured to,

the inner wall has a cylindrical shape, and the main body portion has a non-circular cross section.

5. An expansion valve according to any of claims 1 to 4, characterized in that,

the working rod and the valve core can be in butt joint with each other in a relative displacement mode.