JP6846875B2 - Expansion valve - Google Patents

Description

The present invention relates to an expansion valve having a built-in temperature sensing mechanism used in a refrigeration cycle, and more particularly to an expansion valve in which a power element is attached to a valve body.

Conventionally, for refrigeration cycles used in air conditioners installed in automobiles, a temperature expansion valve with a built-in temperature sensing mechanism that adjusts the amount of refrigerant passing through according to the temperature is used in order to save installation space and piping work. Has been done. The valve body of such an expansion valve has an inlet port into which a high-pressure refrigerant is introduced and a valve chamber communicating with the inlet port, and the top of the valve body is equipped with a drive mechanism for a valve member called a power element. Will be done.
The spherical valve member arranged in the valve chamber faces the valve seat of the valve hole that opens in the valve chamber, and is operated by the valve stem driven by the power element to open the throttle passage between the valve seat and the valve seat. Control the degree.
Further, the refrigerant that has passed through the valve hole is sent from the outlet port to the evaporator side. The refrigerant returning from the evaporator to the compressor side passes through the return passage provided in the valve body.

The power element is composed of an upper lid member that forms a pressure working chamber, a thin diaphragm that elastically deforms under pressure, and a disk-shaped receiving member. The three members are overlapped and the circumferential portion is joined by TIG welding means or the like. Is formed. Further, a stopper member is sandwiched between the diaphragm and the receiving member.
Then, the working gas is sealed in the pressure working chamber formed by the upper lid member and the diaphragm. At this time, in order to fill the pressure working chamber with the working gas, a hole is provided at the top of the upper lid member, the working gas is filled from this hole, the hole is closed with a steel ball or the like, and the pressure working chamber is sealed by projection welding means or the like. Stop.

As the conventional temperature expansion valve with a built-in temperature sensing mechanism as described above, a male screw and a female screw are formed at the opening formed at the top of the valve body of the expansion valve and the bottom of the power element, respectively, and these are screwed. Is known to be fixed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-164208

When starting a general air conditioner, it is necessary to supply as much refrigerant as possible in order to increase the amount of heat exchange, but when shifting to steady operation, fine temperature control is required according to the temperature change in the room. , The expansion valve is required to perform finer flow rate control than large flow rate.
However, when trying to match the control characteristics at the time of starting, for example, in the expansion valve described in Patent Document 1, the flow rate of the expansion valve is increased by increasing the opening area of the valve seat formed in the valve hole. Can be made larger.
On the other hand, if the opening area of the valve seat is increased, the size of the valve body becomes relatively large, and the amount of change in the flow rate with respect to the lift amount of the valve body also becomes large. There is a problem that it becomes difficult to perform fine flow control.

Therefore, an object of the present invention is to provide an expansion valve capable of achieving both a large flow rate mode characteristic at the time of start-up and a steady flow rate mode characteristic at the time of steady operation.

In order to achieve the above object, the expansion valve according to the present invention includes a power element including an upper lid member, a receiving member, a diaphragm sandwiched between the upper lid member and the receiving member, an inlet port, and the inlet. A valve chamber communicating with the port, a valve hole communicating with the valve chamber, an outlet port communicating with the valve hole, a valve seat formed in the opening of the valve hole on the valve chamber side, and a power element attachment. A valve body including a portion, a first valve member having a through hole in the central portion and opening and closing by contacting the valve seat, and a first valve member which opens and closes by contacting the through hole of the first valve member. A second valve member, a support member that supports the second valve member, a first coil spring that supports the support member, and a second valve member that is interposed between the first valve member and the support member. The coil spring 2 is provided with a valve rod attached to the power element to drive the first valve member and the second valve member, and the valve rod has an end portion on the valve chamber side. The first coil is arranged so as to be inserted into the through hole, its end surface contacts the second valve member, and the side portion of the valve rod contacts the first valve member. The spring and the second coil spring are arranged coaxially, and the center of the inner diameter and the outer diameter of the second coil spring is arranged between the inner diameter and the outer diameter of the first coil spring, and the end face thereof. Presses the second valve member to cause displacement, and the second coil urges the first valve member until the side portion comes into contact with the first valve member. It is characterized in that the elastic force of the spring gradually decreases.

In an example of the expansion valve according to the present invention, the first valve member is a cylindrical member, and a tapered surface toward the upper surface thereof is formed on the outer peripheral surface.
Further, the first valve member has a stepped portion on the outer peripheral portion of the lower surface, and one end of the second coil spring is arranged at the stepped portion of the first valve member.

Further, in another example of the expansion valve according to the present invention, the second valve member may be arranged inside the second coil spring.
Further, a small diameter portion and a step portion are formed at the end portion of the valve rod on the valve chamber side, and the step portion comes into contact with the upper surface of the first valve member or faces the end face. A tapered side surface having a reduced diameter may be formed so that the tapered side surface comes into contact with the open end of the through hole of the first valve member.

According to the expansion valve of the present invention, it is possible to provide an expansion valve capable of achieving both a large flow rate mode characteristic at the time of start-up and a steady flow rate mode characteristic at the time of steady operation.
Further, since it is not necessary to increase the size of the second valve member, the conventional type can be used as it is for the support member for supporting the second valve member, the first coil spring, or the valve chamber, and the mode can be switched. It is possible to suppress the cost increase due to the accompanying specification change.

It is a vertical cross-sectional view which shows the expansion valve by a typical example of this invention. It is a partial cross-sectional view which shows the detail of the valve structure of the expansion valve shown in FIG. It is a figure which shows the outline of the 1st valve member by a typical example of this invention, FIG. 3A is a top view, and FIG. 3B is a cross-sectional view of a plane passing through the center. It is sectional drawing which shows the outline of one end of the valve stem by a typical example of this invention. It is a partial cross-sectional view which shows the steady flow rate mode state of the valve structure of the expansion valve shown in FIG. It is a partial cross-sectional view which shows the large flow rate mode state of the valve structure of the expansion valve shown in FIG. It is a graph which shows an example of the flow rate characteristic by the expansion valve of this invention. It is a partial cross-sectional view which shows the detail of the modification of the valve structure in the expansion valve by this invention.

FIG. 1 is a vertical cross-sectional view showing an expansion valve according to a typical example of the present invention.
As shown in FIG. 1, the expansion valve 10 includes a valve body 11, a power element 70, a valve structure 100, an adjusting screw 50, and a valve stem 60.

The valve body 11 of the expansion valve 10 is made of, for example, an aluminum alloy, and can be obtained by extruding an aluminum alloy or the like with the X direction shown in FIG. 1 as the extrusion direction and subjecting the aluminum alloy or the like to machining.
The valve body 11 includes a power element mounting portion 12 formed on the upper surface and having a female screw, an inlet port 20 into which a high-pressure refrigerant is introduced, a refrigerant outlet port 28, a refrigerant return passage 30, and a valve body 11. Has two holes (not shown) penetrating in the X direction of FIG. 1 and a mounting hole (or mounting female screw) 80 for mounting the valve body 11 to other parts.

A female screw hole 11a that opens at the lower end is formed in the lower portion of the valve body 11, and the valve chamber 24 is formed by closing the opening portion of the female screw hole 11a with a plug 50. Further, the inlet port 20 communicates with the valve chamber 24 from the side through the small diameter hole 20a.
On the other hand, an outlet port 28 is formed above the valve chamber 24 in the valve body 11. The outlet port 28 communicates with the upper end portion of the valve chamber 24 via the valve hole 26, and a valve seat 25 is formed on the valve chamber 24 side of the valve hole 26.

The plug 50 is attached in a manner of being screwed into a female screw hole 11a opened at the lower end of the valve body 11, and is rotated by inserting a tool into a hexagonal hole 53 formed on a surface facing the recess 52. The screwing amount can be adjusted.
Further, a sealing member 54 is provided on the outer peripheral portion of the plug 50, whereby the valve chamber 24 is sealed.

A return passage 30 is formed above the outlet port 28 in the valve body 11 so as to penetrate the valve body 11 in the X direction in FIG.
The refrigerant flowing through the expansion valve 10 of the present invention flows in from the inlet port 20, passes through the valve hole 26, is sent out from the outlet port 28, is sent to an evaporator (not shown), and then the refrigerant evaporates. Return from the vessel to the compressor (not shown).
Then, the refrigerant returning from the evaporator to the compressor enters from the left side of the return passage 30 in FIG. 1 and passes through so as to exit to the right side.

A power element mounting portion 12 for mounting the power element 70, which will be described later, is formed above the return passage 30 in the valve body 11.
The power element mounting portion 12 is formed as a bottomed cylindrical hole having a circular opening on the upper surface of the valve body 11 at the upper end of the valve body 11 and an internal thread on the inner wall surface thereof.
Further, a communication hole 31 leading to the return passage 30 is formed in the central portion of the power element mounting portion 12, and a valve rod 60, which will be described later, is inserted therethrough.

The power element 70 includes an upper lid member 71 made of, for example, stainless steel, a receiving member 72 having a through hole at the center, a diaphragm 73 sandwiched between the upper lid member 71 and the receiving member 72, and the diaphragm. It is composed of a stopper member 90 or the like arranged between the 73 and the receiving member 72.
Then, the upper lid member 71, the diaphragm 73, and the receiving member 72 are integrated by peripheral welding at the overlapped end portion.

A pressure actuating chamber 75 is formed between the upper lid member 71 and the diaphragm 73, and after the working gas is sealed in the pressure actuating chamber 75, it is sealed with a sealing plug 76.
The lower portion of the receiving member 72 is cylindrical, and a male screw 72a is formed around the lower portion thereof, and the receiving member 72 is attached to the power element mounting portion 12 by being screwed with the female screw of the power element mounting portion 12 described above.
At this time, a packing 35 is interposed between the power element 70 and the valve body 11.

A through hole 29 is formed between the exit port 28 and the return passage 30. The valve hole 26, the through hole 29, and the communication hole 31 are arranged so that their centers are on the same straight line.
Further, the valve rod 60 is provided so as to be inserted into each of the valve hole 26, the through hole 29, and the communication hole 31.

The upper end side of the valve stem 60 comes into contact with the receiving portion 92 formed on the lower surface of the stopper member 90 of the power element 70, and the lower end side thereof comes into contact with the first valve member 110 and the second valve member 40. Placed in.
With such an arrangement, the expansion valve 10 shown in FIG. 1 receives the movement of the diaphragm 73 deformed in response to the fluctuation of the internal pressure in the pressure operating chamber 75 of the power element 70, and the stopper member 90 moves up and down. The movement of the stopper member 90 is transmitted to the first valve member 110 and the second valve member 40 of the valve structure 100 via the valve rod 60, and can serve as an expansion valve.
Further, the through hole 29 is provided with a spring member 66 for adding a sliding resistance to the outer peripheral surface of the valve rod 60, and vibration between the valve rod 60 and the first valve member 110 and the second valve member 40. To prevent.

FIG. 2 is a partial cross-sectional view showing details of the valve structure of the expansion valve shown in FIG. Note that FIG. 2 shows a case where the expansion valve is in a fully closed state.
As shown in FIG. 2, a valve hole (orifice) 26 having a valve seat 25 is formed between the valve chamber 24 and the outlet port 28.

In the valve chamber 24, a valve structure 100 that opens and closes the valve hole 26 through which the refrigerant flows by contacting or separating from the valve seat 25 is housed.
The valve structure 100 has a first valve member 110 that has a through hole in the center and opens and closes in contact with the valve seat 25, and a second valve member 110 that opens and closes in contact with the through hole of the first valve member 110. A second intervening between the valve member 40, the support member 42 that supports the second valve member 40, the first coil spring 44 that supports the support member 42, and the first valve member 110 and the support member 42. It is composed of 2 coil springs 120 and 2.

The support member 42 includes an upper surface 42a having a conical recess for supporting the second valve member 40 and a flange portion 42b projecting to the side surface, and the lower surface of the flange portion 42b is the first coil. It has a structure that receives one end of the spring 44.
The first coil spring 44 is housed between the lower surface of the flange portion 42b provided on the support member 42 and the recess 52 formed on the plug 50, whereby the second valve member 40 is accommodated on the support member. It is urged toward the side where the valve seat 25 is located via 42.

The first valve member 110 is a cylindrical member, and its outer peripheral surface contacts the valve seat 25 in a fully closed state, and the open end surface of a through hole formed in the central portion (see reference numeral 113 in FIG. 3). ) Is configured to come into contact with the second valve member 40.
A second coil spring 120 is interposed between the lower surface of the first valve member 110 and the upper surface of the flange portion 42b of the support member 42, and the second coil spring 120 is the first. The valve member 110 is urged toward the valve seat 25.
Then, the spring force of the first coil spring 44 and the second coil spring 120 can be adjusted by adjusting the distance between the valve seat 25 and the bottom surface of the recess 52 by changing the screwing amount of the plug 50. ..

The second valve member 40 is a ball-shaped member, which is placed on the upper surface 42a of the support member 42 inside the second coil spring 120, and is a through hole of the first valve member 110 in a fully closed state. It comes into contact with the open end face 113.
Then, the valve rod 60 is arranged so as to insert the through hole of the first valve member 110 so that the end surface of the valve rod 60 on the valve chamber 24 side comes into contact with the second valve member 40.
Here, as shown in FIG. 2, the height from the upper surface of the first valve member 110 to the second valve member 40 in a state where the first valve member 110 and the second valve member 40 are in contact with each other. Assuming that the distance in the direction is H1, the insertion depth (pushing depth) L of the valve stem 60 in the fully closed state is L = H1.

3A and 3B are views showing an outline of a first valve member according to a typical example of the present invention, FIG. 3A is a top view, and FIG. 3B is a cross-sectional view taken along the plane passing through the center. Is.
As described above, the first valve member 110 is a cylindrical member, and a tapered surface 111 toward the upper surface is formed on the outer peripheral surface thereof.

A through hole 112 serving as a passage for the refrigerant is formed in the central portion of the first valve member 110, and an enlarged-diameter tapered opening in contact with the second valve member 40 is formed at the lower end thereof. It has an end face 113.
Further, four notches 114 are formed at equal intervals at the upper end of the enlarged-diameter tapered opening end surface 113.

On the lower surface side of the first valve member 110, a stepped portion 115 having a reduced diameter is formed over the entire circumference.
The step portion 115 serves as a receiving portion that receives the upper end of the second coil spring 120 shown in FIG. 2 and the like.

FIG. 4 is a cross-sectional view showing an outline of one end of a valve stem according to a typical example of the present invention.
As shown in FIG. 4, the valve rod 60 applied to the expansion valve according to the present invention includes a small diameter portion 62 having a reduced diameter at an end portion located on the valve chamber 24 side shown in FIG.
As a result, the end surface 62a and the step portion 60a of the small diameter portion 62 are formed, the small diameter portion 62 is inserted into the through hole 112 of the first valve member 110, and the end surface 62a comes into contact with the second valve member 40. To do.

Here, assuming that the inner diameter of the through hole 112 in the first valve member 110 shown in FIG. 3 is D1, the diameter of the small diameter portion 62 of the valve rod 60 is D2, and the diameter of the valve rod 60 itself is D3, it is between these three. Is formed so that the relationship of "D2 <D1 <D3" is established.
Further, the protruding length H2 of the small diameter portion 62 is formed so as to be sufficiently larger than the distance H1 shown in FIG.

In the expansion valve according to the present invention, when the valve rod 60 attached to the stopper member 90 is pushed down in response to the fluctuation of the diaphragm 73 of the power element 70 shown in FIG. 1, the end of the valve rod 60 on the valve chamber 24 side. The portion pushes down the first valve member 110 and the second valve member 40.
As a result, a part of the valve hole 26 is opened and the refrigerant flows out from the valve chamber 24 to the outlet port 28. The opening / closing operation of the first valve member 110 and the second valve member 40 at this time will be described with reference to FIGS. 5 and 6 below.

FIG. 5 is a partial cross-sectional view showing a steady flow rate mode state of the valve structure of the expansion valve shown in FIG.
As shown in FIG. 5, in the steady flow mode state, the small diameter portion 62 at the tip of the valve rod 60 is inserted into the through hole 112 of the first valve member 110, and the end surface 62a pushes down the second valve member 40. ..
At this time, the insertion depth L of the small diameter portion 62 of the valve stem 60 is set so that “H1 <L <H2”.

In the steady flow rate mode state, the valve rod 60 and the first valve member 110 are not in contact with each other, and the small diameter portion 62 pushes down only the second valve member 40.
Therefore, while the contact between the tapered surface 111 of the first valve member 110 and the valve seat 25 is maintained, a second valve member 110 is located between the open end surface 113 of the first valve member 110 and the second valve member 40. A gap G1 of 1 is formed.

As a result, in the steady flow mode state shown in FIG. 5, the valve seat 25 and the first valve member 110 are closed, and the valve between the first valve member 110 and the second valve member 40 is opened. It will be in the state of being.
At this time, by adjusting the insertion depth L between "H1 <L <H2", the first gap G1 can also be adjusted, so that the flow rate can be finely adjusted by the movement of the valve stem 60. It will be possible.
Further, since the notch 114 is formed at the upper end of the first valve member 110, the flow rate between the upper surface of the first valve member 110 and the step portion 60a of the valve rod 60 increases, and the through hole 112 is formed. The flow of the passing refrigerant becomes smooth.

FIG. 6 is a partial cross-sectional view showing a large flow rate mode state of the valve structure of the expansion valve shown in FIG.
As shown in FIG. 6, in the large flow rate mode state, the small diameter portion 62 at the tip of the valve stem 60 is in contact with the upper surface of the first valve member 110 from the position shown in FIG. The first valve member 110 is also driven to a position where it is pushed down.
At this time, the insertion depth L of the small diameter portion 62 of the valve stem 60 is set to be “H2 <L”.

In the high flow mode state, in addition to the first gap G1 between the first valve member 110 and the second valve member 40, there is also a second gap between the valve seat 25 and the first valve member 110. A gap G2 is formed.
As a result, in the large flow rate mode state shown in FIG. 6, both the valve seat 25 and the first valve member 110 and the first valve member 110 and the second valve member 40 are opened. It will be in a state of being.
At this time, the second gap G2 can be adjusted by adjusting the insertion depth L in the range of "H2 <L", so that the opening and closing with the conventional ball-shaped valve body is compared with the opening and closing. It is possible to flow a larger flow rate of refrigerant.

FIG. 7 is a graph showing an example of the flow rate characteristics of the expansion valve of the present invention. Here, in the graph of FIG. 7, the horizontal axis is the “lift amount”, that is, the pushing down amount of the valve stem 60 based on the fully closed state shown in FIG.
Further, in the graph of FIG. 7, the alternate long and short dash line shows the relationship between the lift amount and the flow rate of the expansion valve due to the conventional small flow rate characteristic, and the broken line indicates the lift amount and the flow rate of the expansion valve due to the conventional large flow rate characteristic. Shows the relationship.

As shown in FIG. 7, the expansion valve according to the present invention is the first expansion valve according to the present invention, as shown in FIG. 6, by adjusting the lift amount to the range R2 in which the lift amount becomes “H2 <L” when the air conditioner or the like is started. The characteristic of the "large flow rate mode" in which the valve is opened between the valve member 110 and the second valve member 40 and between the valve seat 25 and the first valve member 110 can be obtained.
At this time, by appropriately selecting the outer diameter of the first valve member 110, the inclination angle of the tapered surface 111, and the like, it is possible to increase the opening diameter of the valve seat 25 with which the tapered surface 111 abuts, and as a result, , It is possible to control a larger flow rate than when a conventional ball-shaped valve member is used.

On the other hand, during steady operation in which the operation of the air conditioner or the like is stable, the lift amount of the first valve member 110 is adjusted to the range of the region R1 where “H1 <L <H2”, as shown in FIG. The characteristic of the "steady flow rate mode" in which the valve is opened only between the open end surface 113 and the second valve member 40 can be obtained.
At this time, since the contact between the first valve member 110 and the second valve member 40 is apparently equivalent to the relationship between the valve seat and the valve member of the conventional expansion valve, the second valve member 40 The size of can be almost the same as that of the conventional type.

By providing the above-described configuration, according to the expansion valve according to the present invention, the characteristics of the large flow rate mode mainly for opening and closing between the valve seat and the first valve member, and the first valve member and the second valve member are provided. It is possible to switch and use the characteristics of the steady flow rate mode by opening and closing between the valve members and the valve members by adjusting the lift amount according to the pushing depth of the valve stem.
Further, since it is not necessary to increase the size of the second valve member, the conventional type can be used as it is for the support member for supporting the second valve member, the first coil spring, or the valve chamber, and the mode can be switched. It is possible to suppress the cost increase due to the accompanying specification change.

FIG. 8 is a partial cross-sectional view showing details of a modified example of the valve structure in the expansion valve according to the present invention.
Note that FIG. 8 shows a state in which the expansion valve is used in the large flow rate mode, and when the same configuration as that shown in FIGS. 1 to 6 is used, the same reference numerals are given. The explanation will be omitted again.

As shown in FIG. 8, in the expansion valve according to the modified example of the present invention, a reduced diameter small diameter portion 62 and an inclined surface 60c leading to the small diameter portion 62 are formed at the end portion of the valve stem 60 on the valve chamber 24 side. Has been done.
Then, the end surface 62a of the small diameter portion 62 abuts on the second valve member 40 and pushes down, and the inclined surface 60c abuts on the upper end of the through hole 112 of the first valve member 110 and pushes down.

With such a configuration, in addition to the above effects, the base of the small diameter portion 62 is continuously thickened, so that the strength of the tip of the valve stem 60 is improved and the small diameter portion 62 stands upright. Easy to process.
Further, since the inclined surface 60c is formed as a surface whose diameter is smoothly expanded, the refrigerant passing through the through hole 112 of the first valve member 110 can be smoothly flowed without stagnation.

The expansion valve according to the present invention has been described above based on a typical example thereof, but the present invention is not limited to the above specific examples, and various modifications can be made.
For example, a case where a ball-shaped member is used as the second valve member has been illustrated, but if it can be closed by contacting a through hole formed in the first valve member, for example, it has a conical shape or a truncated cone shape. Other shapes such as the above may be adopted.
Further, the second valve member and the support member may be formed as separate bodies, or may be formed as an integral body.

Further, in the above specific example, the case where the power element is attached to the upper end of the valve body by screwing is illustrated, but in addition to this, a cylindrical portion is formed on the upper portion of the valve body and the power element is inserted inside the cylindrical portion. In this state, the power element may be attached by caulking the cylindrical portion inward.
In addition, various modifications can be made to the above examples without departing from the gist of the present invention.

10 Expansion valve 11 Valve body 12 Power element mounting part 20 Inlet port 24 Valve chamber 25 Valve seat 26 Valve hole 28 Outlet port 29 Through hole 30 Return passage 31 Communication hole 40 Second valve member 42 Support member 44 First coil spring 50 Plug 54 Seal member 60 Valve rod 60a Step part 62 Small diameter part 62a End surface 70 Power element 71 Top lid member 72 Receiving member 73 Diaphragm 75 Pressure operating chamber 90 Stopper member 100 Valve structure 110 First valve member 111 Tapered surface 112 Through hole 113 Open end face 114 Notch 115 Step 120 Second coil spring

Claims (6)

A power element including an upper lid member, a receiving member, and a diaphragm sandwiched between the upper lid member and the receiving member.
An inlet port, a valve chamber communicating with the inlet port, a valve hole communicating with the valve chamber, an outlet port communicating with the valve hole, and a valve formed in the opening of the valve hole on the valve chamber side. The valve body including the seat and the power element mounting part,
A first valve member having a through hole in the center and opening and closing in contact with the valve seat,
A second valve member that opens and closes in contact with the through hole of the first valve member,
A support member that supports the second valve member and
A first coil spring that supports the support member and
A second coil spring interposed between the first valve member and the support member,
A valve rod attached to the power element to drive the first valve member and the second valve member,
With
The valve stem is arranged so that the end portion on the valve chamber side is inserted into the through hole, the end surface thereof contacts the second valve member, and the side portion of the valve rod is the first. Contact the valve member of 1
The first coil spring and the second coil spring are arranged coaxially, and the center of the inner diameter and the outer diameter of the second coil spring is between the inner diameter and the outer diameter of the first coil spring. Placed,
The second valve member is urged from the time when the end face presses the second valve member to cause displacement until the side portion comes into contact with the first valve member. An expansion valve characterized in that the elastic force of the coil spring of the coil spring gradually decreases. The expansion valve according to claim 1, wherein the first valve member is a cylindrical member, and a tapered surface toward the upper surface thereof is formed on an outer peripheral surface. The first valve member has a stepped portion on the outer peripheral portion of the lower surface.
The expansion valve according to claim 1 or 2, wherein one end of the second coil spring is arranged at the step portion of the first valve member. The expansion valve according to any one of claims 1 to 3, wherein the second valve member is arranged inside the second coil spring. Claims 1 to 4 are characterized in that a small diameter portion and a step portion are formed at an end portion of the valve rod on the valve chamber side, and the step portion comes into contact with the upper surface of the first valve member. The expansion valve according to any one of the above. At the end of the valve stem on the valve chamber side, a tapered side surface whose diameter is reduced toward the end surface is formed, and the tapered side surface is an opening of the through hole of the first valve member. The expansion valve according to any one of claims 1 to 4, wherein the expansion valve is in contact with an end.

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