CN113574303A

CN113574303A - Expansion valve

Info

Publication number: CN113574303A
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: 2021-10-29
Anticipated expiration: 2040-02-10
Also published as: WO2020189092A1; EP3940279A4; CN113574303B; JP7089769B2; EP3940279A1; EP3940279B1; JP2020148305A; US20220146160A1

Abstract

The present invention provides an improved expansion valve having a simple structure and capable of reducing noise. The expansion valve (10) comprises: a valve body (2) provided with a valve chamber (VS) and a valve seat (20); a valve element (3) that prevents the passage of fluid when seated on the valve seat and allows the passage of fluid when separated from the valve seat; a coil spring (41) that urges the valve element toward the valve seat; and an operating rod (5) that presses the valve element in a direction in which the valve element is separated from the valve seat against a biasing force applied by the coil spring, wherein the valve chamber (VS) has a cylindrical inner wall (24) that is continuous with the valve seat, the valve element (3) has a contact portion (31) that is seated on the valve seat and a cylindrical main body portion (32) that faces the inner wall, and the main body portion has a continuous surface (32b) that is slidable relative to the inner wall and a flat surface (32a) that has a gap between the main 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 used in an air conditioner or the like mounted on an automobile, a temperature-sensitive expansion valve for adjusting the amount of refrigerant passing therethrough in accordance with the temperature is used in order to omit an installation space and piping.

In a general expansion valve, a spherical valve body disposed in a valve chamber is disposed to face a valve seat opening in the valve chamber. The valve body is supported by a valve body support member disposed in the valve chamber, and the valve body 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 member. The valve body is pressed by an operating rod driven by a power element, and is separated from the valve seat to allow the refrigerant to pass therethrough. 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 beginning of the start-up of the refrigeration cycle, the liquid density of the refrigerant passing through the throttle flow passage between the valve seat and the valve body is low, and the flow velocity of the refrigerant increases as the flow resistance decreases. Therefore, at the start-up, the frictional sound at the valve portion is likely to increase, and as a countermeasure therefor, the flow rate of the refrigerant needs to be restricted. On the other hand, in a stable period in which time has elapsed from the start of the refrigeration cycle, the liquid density is higher than that at the start of the refrigeration cycle, and therefore the frictional sound is reduced. Therefore, there is a reverse demand that excessive flow rate restriction is not required in the steady state, and a sufficient refrigerant flow rate is desired to be secured.

In contrast, patent document 1 discloses an expansion valve in which a refrigerant inlet to a valve chamber and a clearance between a valve body support and the valve chamber are defined so that a reduction in frictional noise of the refrigerant at the time of starting the refrigeration cycle and a required flow rate of the refrigerant passing through a throttle passage are both achieved in a balanced manner.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5369259

Technical problem to be solved by the invention

On the other hand, noise other than frictional sound of the refrigerant is also generated in the expansion valve. For example, in the expansion valve disclosed in patent document 1, bubbles in the refrigerant reach the valve seat in an unbroken state, and the bubbles are broken at the same time when the refrigerant passes through the valve seat, and may be perceived as noise.

Disclosure of Invention

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

Means for solving the problems

In order to achieve the above object, an expansion valve according to the present invention includes: a valve body provided with a valve chamber and a valve seat; a valve element that restricts passage of fluid when seated on the valve seat and allows passage of fluid when separated from the valve seat; a coil spring that urges the valve element toward the valve seat; and an operating rod that presses the valve body against an urging force applied by the coil spring in a direction in which the valve body separates from the valve seat, wherein the valve chamber has a cylindrical inner wall that is continuous with the valve seat, the valve body has a contact portion that is seated on the valve seat and a cylindrical main 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 main body portion, so that a space through which the fluid passes is formed between the inner wall and the main body portion, and the inner periphery of the inner wall and the outer periphery of the main body portion are in partial sliding contact.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide an improved expansion valve having a simple structure and capable of reducing noise.

Drawings

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

Fig. 2 is a sectional view taken along line a-a of fig. 1 as viewed from above.

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

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

Fig. 5 is a sectional view of fig. 4 taken along line B-B from a top view.

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

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

Fig. 8 is a sectional view of fig. 7 taken along line C-C from above.

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

Fig. 10 is a sectional view of a body part of a modification.

Detailed Description

(definition)

In the present specification, a direction from the valve body 3 toward the operation rod 5 is defined as an "upward direction", and a direction from the operation rod 5 toward the valve body 3 is defined as a "downward direction". Therefore, in the present specification, the direction from the valve body 3 toward the operation rod 5 is referred to as an "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 line with four or more planes. However, when there is a connected plane connecting the planes to each other, it is assumed that the connected plane is not included in the planes. In addition, "the shape of the inner periphery in 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 an 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, thereby constituting the refrigerant cycle system 100.

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

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

Fig. 2 is a sectional view taken along line a-a of fig. 1, which is a plan view of the valve body 3. Fig. 3 is a perspective view of the valve body 3. In fig. 3, the valve element 3 is formed by connecting a conical contact portion 31, a hexagonal cylindrical body portion 32, a disc-shaped flange portion 33, and a cylindrical end portion 34.

The tapered surface 31b of the abutment portion 31 abuts against the valve seat 20. The upper surface 31a of the contact 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 the 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 equal times the diameter of the inner wall 24 of the valve chamber VS (or the maximum length of the diagonal line 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 body portion 32, and the inner wall 24 of the valve chamber VS slides in contact with any one of the connecting surfaces 32b due to the eccentricity of the valve chamber VS and the spool 3. On the other hand, the inner wall 24 of the valve chamber VS does not abut against the flat surface 32a regardless of the eccentricity of the valve chamber VS and the spool 3. Therefore, the refrigerant passes through the space between the inner wall 24 and the flat surface 32 a.

In fig. 1, when the valve body 3 is seated on the annular valve seat 20 of the valve main body 2, the first flow passage 21 and the second flow passage 22 are in a non-communicating 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 a communicating state. However, there may be a case where a limited amount of refrigerant passes when the valve element 3 is seated on the valve seat 20.

The lower end of the operating rod 5 inserted through the operating rod insertion hole 28 of the valve main body 2 and the orifice portion 27 with a gap 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 device 4. When the operation rod 5 moves downward, the valve element 3 is separated from the valve seat 20, and the expansion valve 10 is opened.

Next, the power element 8 for driving the work bar 5 will be explained. In fig. 1, the power element 8 is attached to a recess 2a provided in the top of the valve body 2. The recess 2a communicates with a return flow path 23 in the valve main body 2 through which the refrigerant from the evaporator 104 passes, via a communication path 2 b. The work rod 5 passes through the communication path 2 b. A female screw is formed on the inner periphery of the recess 2 a.

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 has 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 a plug 81.

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

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

Receiving member 86 includes: a flange portion 86a having an outer diameter substantially equal to the outer diameter of the flange portion 82b of the upper cover member 82, a step portion 86c having an annular bearing surface 86b substantially orthogonal to the axis L, and a hollow cylindrical portion 86 d. A male screw is formed on the outer periphery of the hollow cylindrical portion 86 d.

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

The outer peripheral portions of flange portion 82b of upper lid member 82, diaphragm 83, and flange portion 86a of receiving member 86 are integrally formed by circumferential welding such as TIG welding, laser welding, or plasma welding while overlapping the outer peripheral portions.

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

At this time, the diaphragm 83 receives pressure so as to protrude toward the receiving member 86 by the working gas sealed in the pressure working chamber PO, and is supported 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.

When the power element 8 is assembled, the power element 8 is fixed to the valve body 2 by screwing 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 in a state where the upper end of the operating rod 5 is fitted into the fitting hole 84a of the stopper member 84.

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

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

The biasing device 4 includes a coil spring 41 that winds a circular wire into a spiral shape, and a spring receiving member 43. The spring receiving member 43 has a function of sealing an opening of the valve chamber VS of the valve body 2 and a function of supporting a 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, and prevents 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 portion 34 of the valve body 3 is fitted into the upper end inner side of the coil spring 41, whereby the valve body 3 shown in fig. 3 is held.

(operation of expansion valve)

An operation example of the expansion valve 10 will be described with reference to fig. 1. The refrigerant pressurized by the compressor 101 is liquefied by 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 in 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 the non-communicating 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 passes through the orifice portion 27 and the second flow path 22 and is sent to the evaporator 104.

According to the present embodiment, when the abutment portion 31 of the valve body 3 is separated from the valve seat 20, the refrigerant containing bubbles in the valve chamber VS gradually bursts while passing through a relatively narrow gap between the flat surface 32a of the body portion 32 and the inner wall 24 over the axial length of the body portion 32 of the valve body 3. Therefore, the bubbles do not break at once when the refrigerant passes through the valve seat 20, and the energy at the time of the bubble breaking can be reduced to reduce the passing sound. Further, the flow of the refrigerant along the flat surface 32a extending along the axial length of the body portion 32 provides a flow straightening effect of the refrigerant.

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

In fig. 1, a pressure working chamber PO and a pressure detection chamber PD partitioned by a diaphragm 83 are provided inside the power element 8. Therefore, when the working gas in the pressure working chamber PO is liquefied, the working rod 5 moves in the upward direction, and when the liquefied working gas is vaporized, the working rod 5 moves in the downward direction. In this way, the expansion valve 10 is switched between the valve-opened state and the valve-closed state.

Further, the pressure detection chamber PD of the power element 8 communicates with the return flow path 23. Therefore, the pressure of the refrigerant flowing through the return flow path 23 is transmitted to the working gas in the pressure working chamber PO via the stopper member 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 in accordance with 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 cross-sectional view showing the vicinity of the valve element of the expansion valve 10A. Fig. 5 is a sectional view of fig. 4 taken along line B-B from a top view. 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 abutment portion 31A abuts against the valve seat 20. The upper surface 31Aa of the contact portion 31A is a plane orthogonal to the axis L. The outer periphery of the body portion 32A is formed by six flat surfaces 32Aa and a connecting surface 32Ab formed between the adjacent flat surfaces 32 Aa. The connecting surface 32Ab may be a flat surface or a curved surface. The length of the body portion 32A is preferably equal to or more than equal times the diameter of the inner wall 24A of the valve chamber VS (or the maximum length of the diagonal line of the body portion 32A). The continuous 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. The other structures are the same as those of the above-described embodiment, and therefore the same reference numerals are given thereto, and redundant description thereof is omitted.

According to the present embodiment, when the contact portion 31A of the valve element 3A is separated from the valve seat 20, the bubbles are gradually broken while the refrigerant containing the bubbles in the valve chamber VS passes through the relatively narrow gap between the flat surface 32Aa of the body portion 32A and the inner wall 24A over the axial length of the body portion 32A of the valve element 3A. Therefore, the bubbles do not break at once when the refrigerant passes through the valve seat 20, and the energy at the time of the bubble breaking can be reduced to reduce the passing sound. Further, the flow of the refrigerant along the flat surface 32Aa extending along the axial length of the body portion 32A provides a flow straightening effect of the refrigerant.

When the valve is opened or closed, the continuous surface 32Ab of the main body portion 32A that is in contact with the inner wall 24A has a long span corresponding to the axial length of the main body portion 32A, and therefore, the inclination that occurs when the contact portion 31A of the valve body 3A is separated from the valve seat 20 can be suppressed. Therefore, smooth operation of the valve body 3A can be ensured in accordance with the relative displacement of the upper surface 31Aa and the operating rod 5.

In particular, since the abutment position of the abutment surface 32Ab with the inner wall 24A is relatively distant 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 cross-sectional view showing the vicinity of the valve element of the expansion valve 10B. Fig. 8 is a sectional view of fig. 7 taken along line C-C from above. 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 disc-shaped flange portion 33B, and a cylindrical end portion 34B.

The tapered surface 31Bb of the abutment portion 31B abuts against the valve seat 20. The upper surface 31Ba of the contact 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 length of the diagonal line 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 tubular shape formed by six flat surfaces 24 Bb. The outer periphery of the main body portion 32B of the spool 3B contacts the flat surface 24Bb at any of the six tangent points CP shown in fig. 8. Therefore, the contact point CP on the outer peripheral surface of the body portion 32B constitutes a sliding contact portion, and the outer peripheral surfaces between adjacent contact points CP constitute a flow path portion. The other structures are the same as those of the above-described embodiment, and therefore the same reference numerals are given thereto, and redundant description thereof is omitted.

According to the present embodiment, when the abutment portion 31B of the valve element 3B is separated from the valve seat 20, the refrigerant containing bubbles in the valve chamber VS gradually bursts while passing 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 element 3B. Therefore, the bubbles do not break at once when the refrigerant passes through the valve seat 20, and the energy at the time of the bubble breaking can be reduced to reduce the passing sound. Further, the flow of the refrigerant is distributed over the flat surface 24Bb along the axial length of the body portion 32B, thereby obtaining a flow rectification effect of the refrigerant.

Since the flat surface 24Bb in contact with the main body portion 32B has a long span in the axial direction of the valve element 3B when the valve is opened or closed, the inclination that occurs when the contact portion 31B of the valve element 3B separates from the valve seat 20 can be suppressed. Therefore, smooth operation of the valve body 3B can be ensured in accordance with the relative displacement between the upper surface 31Ba and the operating rod 5.

(modification example)

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 portion 32D of the valve body 2D has a non-circular cross section with respect to the inner wall 24D of the valve chamber as a cylindrical surface. Specifically, the main body portion 32D is formed of a partially 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 body portion 32D is the same over the entire length of the body portion 32D. The partial cylindrical surface 32Da constitutes a sliding contact portion, and the flat surface 32Db constitutes a flow path portion. The other structures are the same as those of the above-described embodiment, and therefore the same reference numerals are given thereto, and redundant description thereof is omitted.

According to the present modification, when the valve body is separated from the valve seat, the bubbles are gradually broken while the refrigerant containing the bubbles in the valve chamber passes through the relatively narrow gap between the flat surface 32Db of the body portion 32D and the inner wall 24D over the axial length of the body portion 32D of the valve body. Therefore, the bubbles do not break at once when the refrigerant passes through the valve seat, and the energy at the time of breaking the bubbles can be reduced to reduce the passing sound. Further, the flow of the refrigerant along the flat surface 32Db extending along the axial length of the body portion 32D provides a flow straightening effect of the refrigerant.

The present invention is not limited to the above-described embodiments. Within the scope of the present invention, any component of the above-described embodiments may be modified. In the above-described embodiment, any component can 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.

Description of the symbols

10. 10A, 10B expansion valve

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

3. 3A, 3B valve core

4 force applying 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 annular part

27 throttle hole part

41 helical spring

42 spool support

43 spring receiving part

100 refrigerant cycle system

101 compressor

102 condenser

104 evaporator

VS valve chamber.

Claims

1. An expansion valve, comprising:

a valve body provided with a valve chamber and a valve seat;

a valve element that restricts passage of fluid when seated on the valve seat and allows passage of fluid when separated from the valve seat;

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

a working rod that presses the valve element against a biasing force applied by the coil spring in a direction in which the valve element is separated from the valve seat,

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

the valve element has a contact portion that is seated on the valve seat and a cylindrical body portion that faces the inner wall,

when a cross section is taken in a direction orthogonal to the axis of the valve body, the shape of the inner periphery of the inner wall is made different from the shape of the outer periphery of the main body portion, so that a space through which the fluid passes is formed between the inner wall and the main body portion, and the inner periphery of the inner wall and the outer periphery of the main body portion are in partial sliding contact.

2. An expansion valve according to claim 1,

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

3. An expansion valve according to claim 1,

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

4. An expansion valve according to claim 1,

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

5. An expansion valve according to any of claims 1-4,

the working rod is in contact with the valve core in a relatively displaceable manner.