JP2017172654A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain good operational responsiveness of a shaft even when an expansion valve is miniaturized. An expansion valve 100 passes a first refrigerant passage 112 for passing a refrigerant supplied from a condenser 102 toward an evaporator 104 and a refrigerant supplied from the evaporator 104 toward the condenser 102. It has a second refrigerant passage 114. The power element 120 generates a driving force according to the temperature of the refrigerant passing through the second refrigerant passage 114. The shaft 122 is displaced by the driving force of the power element 120. The valve body 118 opens and closes the first refrigerant passage 112 according to the displacement of the shaft 122. A vibration-proof spring 148 is interposed between the body 116 and the shaft 122. The shaft 122 has a large diameter portion, a large diameter portion 150 having a large outer diameter, and a small diameter portion 152 having a small outer diameter, and prevents the first refrigerant passage 112 from being closed to a maximum valve opening state. The oscillating spring 148 comes into contact with the small diameter portion 152. [Selection diagram] Fig. 1

Description

  The present invention relates to an expansion valve, and more particularly to a shaft structure of an expansion valve.

  Automobile air conditioners (car air conditioners) exchange heat by repeatedly evaporating and liquefying refrigerants such as alternative chlorofluorocarbons. Specifically, heat is removed from the environment by evaporating (vaporizing) the refrigerant with an evaporator, and heat is released from the refrigerant by returning the vaporized refrigerant to a liquid with a condenser.

  Since the gas is liable to be liquefied under high pressure, the refrigerant recovered from the evaporator is compressed by the compressor and then sent to the condenser. After the refrigerant sent out from the condenser is gas-liquid separated by the receiver, its pressure is lowered by expansion of the expansion valve. This is to make it easier to evaporate the refrigerant by lowering the pressure of the refrigerant.

  The expansion valve (temperature expansion valve) increases the amount of refrigerant supplied from the condenser to the evaporator when the temperature of the refrigerant derived from the evaporator (hereinafter referred to as “evaporation temperature”) is high. When the evaporation temperature is low, the degree of refrigerant superheat is controlled by reducing the amount of refrigerant supplied from the condenser to the evaporator.

  The expansion valve has a first refrigerant passage that allows the refrigerant supplied from the condenser to the evaporator to pass therethrough, and a second refrigerant passage that allows the refrigerant supplied from the evaporator to the compressor to pass therethrough. A temperature-dependent actuator (drive unit) called a power element is installed in the upper part of the second refrigerant passage. The power element displaces the shaft according to the evaporation temperature of the refrigerant passing through the second refrigerant passage. The shaft functions as an “operating rod” that controls the opening of the valve body of the first refrigerant passage, that is, the amount of refrigerant supplied from the condenser to the evaporator, by the displacement (see Patent Document 1).

JP2013-242129A

  In recent years, there has been a demand for further reduction in size and weight of the expansion valve, and accordingly, the size of the power element needs to be reduced. As the power element becomes smaller, the driving force also becomes smaller, so that the movement of the shaft (operation response) becomes dull. For this reason, in order to realize the miniaturization of the power element, a measure for improving the operation response of the shaft is required.

  The present invention has been completed based on the recognition of the above problems by the present inventors, and its main purpose is to improve the operation responsiveness of the shaft of the expansion valve, particularly even when the expansion valve is downsized. The purpose is to maintain the operational response of the shaft well.

The expansion valve of the present invention includes a first refrigerant passage that allows the refrigerant that has flowed in through the heat exchanger to pass toward the evaporator, and a second refrigerant passage that allows the refrigerant returned from the evaporator to pass toward the compressor. And a body that includes a body, a drive unit that generates a driving force according to the pressure and temperature of the refrigerant that passes through the second refrigerant passage, and a partition that passes through the partition walls of the first and second refrigerant passages, and is displaced by the driving force. An actuating rod that is installed in the first refrigerant passage, opens and closes the first refrigerant passage according to the displacement of the actuating rod, and is interposed between the body and the actuating rod and prevents contact with the actuating rod. A vibration spring.
The actuating rod has a large-diameter portion and a small-diameter portion whose outer diameter is smaller than the large-diameter portion, and in the section from the closed state of the first refrigerant passage to the maximum open state, the vibration-proof spring has a small diameter. Contact at the part.

  The contact resistance between the vibration isolating spring and the shaft can be reduced by bringing the shaft (actuating rod) into contact with the vibration isolating spring through a small diameter portion having a relatively small outer diameter. Such a device facilitates smooth movement of the shaft of the expansion valve.

  According to the present invention, it becomes easy to improve the operation responsiveness of the shaft of the expansion valve.

It is sectional drawing of the expansion valve which concerns on 1st Embodiment. It is an enlarged view of the area | region A of FIG. 1 in a maximum valve opening state. It is a schematic diagram of the shaft periphery in 2nd Embodiment. It is an enlarged view of the area | region A in the maximum valve opening state of 2nd Embodiment. It is sectional drawing of the expansion valve in 3rd Embodiment. It is an enlarged view of the area | region A of FIG. 5 in a maximum valve opening state.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, for the sake of convenience, the positional relationship between the structures may be expressed based on the illustrated state. In the following embodiments and modifications thereof, substantially the same components are denoted by the same reference numerals, and the description thereof may be omitted as appropriate.

[First Embodiment]
FIG. 1 is a cross-sectional view of an expansion valve 100 according to the first embodiment.
The expansion valve 100 in this embodiment is used in the car air conditioner 110.
The car air conditioner 110 is filled with a refrigerant that easily evaporates even at a low temperature, such as an alternative chlorofluorocarbon, and the refrigerant circulates through the compressor 106, the condenser 102 as an external heat exchanger, the receiver 108, and the evaporator 104. The evaporator 104 takes in external heat into the refrigerant by vaporizing the refrigerant (cooling function). The compressor 106 applies pressure to the gaseous refrigerant to facilitate liquefaction of the refrigerant. The condenser 102 returns the refrigerant whose pressure has been increased by the compressor 106 to a liquid. At this time, heat is exhausted from the refrigerant to the outside. The receiver 108 gas-liquid separates the refrigerant.

The expansion valve 100 adjusts the flow of refrigerant from the condenser 102 to the evaporator 104. Further, it also serves as a refrigerant path from the evaporator 104 to the compressor 106.
The body 116 of the expansion valve 100 is a member obtained by extruding a material made of an aluminum alloy and performing predetermined machining. The body 116 includes a first refrigerant passage 112 that sends the refrigerant supplied from the compressor 106, the condenser 102, and the receiver 108 to the evaporator 104, and a second refrigerant that returns the refrigerant supplied from the evaporator 104 to the compressor 106. A passage 114 is formed.
The power element 120 is fixed to the upper part of the body 116 with screws or the like. An O-ring 166 is interposed between the power element 120 and the body 116 to prevent refrigerant leakage. A screw hole 126 for pipe attachment is formed on the side surface of the body 116.

  A ball-shaped valve body 118 is provided in the middle of the first refrigerant passage 112 to adjust the opening. A rod-shaped shaft 122 is inserted through the body 116 of the expansion valve 100. The lower end of the shaft 122 is in contact with the valve body 118, and the upper end is in contact with the disk 124 built in the power element 120. The refrigerant passes through the gap between the valve body 118 and the valve hole 168. When the valve body 118 moves downward (opening direction) in FIG. 1, the gap (opening) between the valve body 118 and the valve hole 168 increases. A “valve” of the first refrigerant passage 112 is formed by the valve hole 168, the valve body 118, and the valve body receiver 142 that supports the valve body 118.

The power element 120 (driving unit) functions as an actuator that generates a driving force according to temperature. In the power element 120, an upper housing 130 and a lower housing 132 are disposed above and below a diaphragm 128 (metal thin plate), and the outer peripheral edge portions thereof are welded. A gas having a temperature characteristic similar to that of a refrigerant is sealed in an upper sealed space 134 formed by the upper housing 130 and the diaphragm 128. A disk 124 is accommodated in the temperature sensitive room 136 formed by the lower housing 132. The lower part of the temperature-sensitive greenhouse 136 is opened, and the second refrigerant passage 114 and the temperature-sensitive room 136 communicate with each other through a connection path 138 formed as an opening in the body 116. For this reason, a part of the refrigerant flowing from the evaporator 104 through the second refrigerant passage 114 to the compressor 106 also flows into the sensitive room 136. The refrigerant evaporating temperature is transmitted to the sealed space 134 via the disk 124.
In addition, by adjusting the diameter of the connecting path 138, the amount of refrigerant flowing from the second refrigerant passage 114 into the sensitive room 136 is controlled, and the time constant is adjusted.

In the sealed space 134, the saturation pressure of the gas changes according to the evaporation temperature. When the evaporation temperature is high, the saturation pressure increases, and the shaft 122 is pushed downward in FIG. 1 (the valve opening direction) through the diaphragm 128 and the disk 124. The valve body 118 is urged upward in FIG. 1 by the spring 140 via the valve body receiver 142, but when the force to push down the shaft 122 becomes strong, the valve body 118 is also pushed down.
The greater the amount of downward displacement of the shaft 122, in other words, the higher the evaporation temperature, the greater the valve opening of the first refrigerant passage 112 and the greater the amount of refrigerant flowing through the first refrigerant passage 112.

  On the contrary, when the evaporation temperature is low, the saturation pressure in the sealed space 134 becomes small, the valve body 118 is pushed up by the biasing force of the spring 140, and the first refrigerant passage 112 is closed. The refrigerant passing through the first refrigerant passage 112 by the valves (the valve body 118 and the valve hole 168) is squeezed and expanded to form a mist.

  The shaft 122 is inserted into a through passage 144 formed in the body 116. The shaft 122 contacts the valve body 118. Further, the disk 124 contacts the shaft 122. The valve body 118, the disk 124, and the shaft 122 need not be integrally joined to each other. In order to prevent the refrigerant from leaking between the second refrigerant passage 114 and the first refrigerant passage 112, it is desirable to make the gap (clearance) between the outer surface of the shaft 122 and the inner surface of the through passage 144 as small as possible.

In summary, according to the above configuration, when the degree of superheat of the refrigerant flowing from the evaporator 104 to the expansion valve 100 is high, the valve body 118 is pushed down and the valve opening degree of the first refrigerant passage 112 is increased. Thus, the amount of refrigerant passing through the first refrigerant passage 112 increases, and the degree of superheat of the refrigerant is reduced. When the degree of superheat is low, the valve body 118 is pushed up, the valve opening degree of the first refrigerant passage 112 is reduced, the amount of refrigerant passing through the first refrigerant passage 112 is reduced, and the degree of superheat is increased. By automatically adjusting the flow rate of the refrigerant, the degree of superheat is adjusted around the set value.
An adjustment screw 146 is attached to the lower part of the spring 140. The set value determined by the urging force of the spring 140 can be adjusted by the screwing amount of the adjustment screw 146.

  Further, a vibration-proof spring 148 abuts on the shaft 122. The anti-vibration spring 148 is a leaf spring having the shape shown in Patent Document 1. Specifically, the anti-vibration spring 148 is a cylindrical body having a triangular cross section having flat side walls, and spring portions are integrally formed on the three side walls. When the shaft 122 receives a lateral load from the anti-vibration spring 148, vibration of the shaft 122 and the valve body 118 due to fluctuations in the refrigerant pressure is suppressed.

  When considering miniaturization of the expansion valve 100, the power element 120 (sealed space 134, disk 124, etc.) also needs to be miniaturized. When the power element 120 is reduced, the driving force of the power element 120 is also reduced. When the driving force of the power element 120 is reduced, the movement of the shaft 122 when the evaporation temperature changes (operation responsiveness: drivability for changing from a stationary state to a moving state) becomes dull.

  As described above, since the anti-vibration spring 148 contacts the shaft 122, the contact resistance accompanying the contact restricts the displacement of the shaft 122. According to the study by the present inventors, it has been found that the contact resistance (frictional force) caused by the contact between the vibration-proof spring 148 and the shaft 122 has a great influence on the decrease in the operation responsiveness of the shaft 122.

  Therefore, in the first embodiment, the contact resistance between the anti-vibration spring 148 and the shaft 122 is reduced by reducing the diameter of the portion of the shaft 122 that contacts the anti-vibration spring 148. More specifically, the shaft 122 is provided with large diameter portions 150a, 150b (hereinafter collectively referred to as “large diameter portion 150”) having relatively large diameters and a small diameter portion 152 having a relatively small diameter therebetween. Forming. The shaft 122 is preferably symmetrical in the vertical direction. In this case, the small diameter portion 152 is formed at a position including the midpoint of the shaft 122. If the shaft 122 is vertically symmetric, the assembling operator does not have to worry about the vertical direction of the shaft 122 at the time of manufacture, so the manufacturing burden is reduced.

FIG. 2 is an enlarged view of a region A in FIG. 1 in a maximum valve opening state.
The outer diameter of the small diameter portion 152 is smaller than the outer diameter of the large diameter portion 150. The outer diameter of the small diameter portion 152 is 99.5% or less, preferably 99% or less, than the outer diameter of the large diameter portion 150.

  The anti-vibration spring 148 is formed with a protrusion 156 (support portion). The protrusions 156 are respectively formed on the three side surfaces of the vibration-proof spring 148, and the small-diameter portion 152 is supported by the three protrusions 156 from three directions. The shaft 122 may vibrate in the vertical direction due to the movement of the refrigerant. Such swinging of the shaft 122 is alleviated by the support by the protrusion 156.

  As described above, since the shaft 122 is displaced up and down by the power element 120, the place where the shaft 122 abuts on the protrusion 156 is also displaced. A contactable region 154 shown in FIG. 2 conceptually shows a region that may come into contact with the protrusion 156 due to the displacement of the shaft 122. The shaft 122 in the first embodiment does not abut on the projection 156 and the large diameter portion 150, and always abuts on the small diameter portion 152. In other words, the protrusion 156 always abuts against the small diameter portion 152 from when the downward displacement of the shaft 122 is minimized (when the valve is closed) to when the downward displacement of the shaft 122 is maximized (when the valve is fully opened). Compared with the case where the protrusion 156 contacts the large diameter portion 150, the contact force with the small diameter portion 152 weakens the support force of the anti-vibration spring 148, but the operation responsiveness of the shaft 122 improves.

The pressure of the refrigerant flowing through the second refrigerant passage 114 pulsates little by little. When the power element 120 senses this pulsation, the shaft 122 swings up and down, and the valve body 118 repeats opening and closing. When the valve body 118 is repeatedly opened and closed, the high-pressure refrigerant passing through the first refrigerant passage 112 from the receiver 108 also pulsates greatly. The anti-vibration spring 148 suppresses such swinging of the shaft 122.
In the present embodiment, the shaft 122 has a smaller driving force due to a reduction in the size of the power element 120 (a reduction in the pressure receiving area of the disk 124). As a result, the shaft 122 is less likely to swing compared to the conventional expansion valve 100, so there is room for reducing the support force provided by the vibration-proof spring 148. Therefore, in the expansion valve 100 according to the present embodiment, the contact resistance with the anti-vibration spring 148 (protrusion 156) is reduced by forming the small diameter portion 152 on the shaft 122. Reducing the contact resistance of the anti-vibration spring 148 greatly contributes to improving the operation response of the shaft 122. In other words, the shaft 122 is provided with the small-diameter portion 152 and the small-diameter portion 152 is supported by the protrusion 156, thereby optimizing the balance between the operation responsiveness and the vibration-proof property.

  Instead of providing the small-diameter portion 152 on the shaft 122, a method of replacing the anti-vibration spring 148 with a weaker supporting force may be considered. However, since the anti-vibration spring 148 is a small part of several millimeters, it is difficult to identify the type of the anti-vibration spring 148. In this case, although it is a small expansion valve 100, there is a concern about a manufacturing error that the vibration-proof spring 148 for the large expansion valve 100 is misused. On the other hand, since the shaft 122 having the small diameter portion 152 and the shaft 122 that is not so are obvious at a glance, such a manufacturing error hardly occurs.

The small diameter portion 152 in the present embodiment is formed by rolling after the shaft 122 is formed by cutting. Since it is a rolling process, the small diameter portion 152 is considered to be harder than the large diameter portion 150, and this is also considered to contribute to reducing the contact resistance between the shaft 122 and the protrusion 156. The rolled surface and the cut surface can be visually identified with a loupe. It is not essential to provide a step between the large diameter portion 150 and the small diameter portion 152. The small diameter portion 152 may be formed so that at least the average outer diameter of the contactable region 154 is smaller than the average outer diameter of the large diameter portion 150.
As shown in FIG. 1, the shaft 122 according to the first embodiment has the smallest outer diameters at both ends, the largest outer diameters of the two large diameter portions 150 inside the both ends, and the two large diameter portions 150. The outer diameter of the central shaft 122 sandwiched between the two is intermediate.

[Second Embodiment]
FIG. 3 is a schematic view around the shaft 122 in the second embodiment.
The basic structure of the shaft 122 in the second embodiment is the same as that of the shaft 122 in the first embodiment. The through passage 144 formed in the body 116 includes a large passage 158 having a relatively large inner diameter and a small passage 160 having a relatively small inner diameter. In the second embodiment, the small diameter portion 152 faces the boundary B between the large passage 158 and the small passage 160. The large diameter portion 150 of the shaft 122 slides in the small passage 160. The large passage 158 has an inner diameter larger than the outer diameter of the large-diameter portion 150 in order to accommodate the vibration-proof spring 148.

The large passage 158 is formed by drilling from above the body 116 with a drill having a relatively large diameter. The small passage 160 is formed by drilling from below the body 116 with a drill having a relatively small diameter after the formation of the large passage 158. By drilling with a small drill until it reaches the large passage 158, a through passage 144 through the body 116 is formed.
More precisely, the boundary B corresponds to the intersection of the tapered portion 168 and the small passage 160 formed by the tip of the drill when the large passage 158 is formed.

  When the through passage 144 having two types of inner diameters is formed by the above manufacturing method, a burr 162 (break) may occur at the boundary B between the large passage 158 and the small passage 160. When the shaft 122 is displaced, if the shaft 122 bites the burr 162, the operation responsiveness of the shaft 122 is deteriorated.

FIG. 4 is an enlarged view of the region A in the maximum valve opening state of the second embodiment.
In the second embodiment, all the regions (opposed regions 164) that may face the boundary B due to the displacement of the shaft 122 are formed in the small diameter portion 152. That is, in the second embodiment, the boundary B (oppositeable region 164) does not face the large diameter portion 150 of the shaft 122, and always faces the small diameter portion 152. Since the outer diameter of the small diameter portion 152 is smaller than the inner diameter of the small passage 160, the burr 162 does not restrict the operation of the shaft 122.

  It is also possible to combine the first and second embodiments. That is, both the contactable area 154 and the facing area 164 may be formed in the small diameter portion 152. The abutable area 154 and the opposed area 164 may partially overlap.

[Third Embodiment]
FIG. 5 is a cross-sectional view of the expansion valve 100 in the third embodiment. FIG. 6 is an enlarged view of a region A in FIG. 5 in the maximum valve opening state.
The difference between the first and second embodiments and the third embodiment lies in the shape of the power element 120, particularly the disk 124 accommodated in the power element 120. A part of the lower surface of the disk 124 in the third embodiment protrudes to the inside of the connection path 138. For this reason, the contact area between the refrigerant passing through the second refrigerant passage 114 and the disk 124 increases.

  When the power element 120 is downsized, the driving force of the power element 120 is reduced. One of the causes is that the contact area of the disk 124 with the refrigerant is reduced. Therefore, as in the third embodiment, a part of the disk 124 is protruded from the temperature-sensitive room 136 to the connection path 138 to increase the contact area with the refrigerant, thereby making it easy to transmit the evaporation temperature to the sealed space 134.

  The shaft 122 is configured such that the small diameter portion 152 is sandwiched between the two large diameter portions 150. The shaft 122 is desirably vertically symmetrical for the reasons described above, and it is desirable that both the abuttable region 154 and the opposed region 164 are included in the small diameter portion 152. The thickness of the disk 124 (the distance from the upper surface in contact with the diaphragm 128 to the portion in contact with the shaft 122) may be adjusted so as to satisfy the above design conditions.

  Since the strength of the shaft 122 is reduced in the small diameter portion 152, it is desirable that the small diameter portion 152 is short. In order to maintain the vertically symmetrical shape while shortening the small diameter portion 152, the length of the shaft 122 may be restricted. Also in this case, the design condition may be satisfied by adjusting the thickness of the disk 124.

In the above, based on embodiment, it demonstrated centering on the shape of the expansion valve 100, especially the shaft 122. FIG.
According to the present embodiment, even if the power element 120 is downsized and its driving force is reduced, the operation responsiveness is improved by reducing the contact resistance between the anti-vibration spring 148 and the shaft 122. In other words, in the small expansion valve 100, the trade-off between operation responsiveness and vibration isolation is optimized. Further, the small diameter portion 152 of the shaft 122 is opposed to the boundary B so that the burr 162 formed at the time of drilling the through passage 144 does not restrict the displacement of the shaft 122. Furthermore, in the third embodiment, in order to compensate for a decrease in the driving force of the power element 120, a part of the disk 124 is protruded to the sensitive room 136, thereby increasing the conductivity of the evaporation temperature.

  By forming the anti-vibration spring 148 on the shaft 122, the anti-vibration spring 148 common to both the small expansion valve 100 and the large expansion valve 100 can be used. Moreover, the manufacturing error of the expansion valve 100 can be suppressed by making the shaft 122 symmetrical in the vertical direction.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and various modifications can be made within the scope of the technical idea of the present invention. Nor. For example, some components may be combined in the above-described embodiment and modification, or some components may be deleted from each embodiment and modification.

  Although not described in the above embodiment, a seal member such as an O-ring is provided between the shaft 122 (small passage 160) and the shaft 122 shown in FIG. 1, and the first refrigerant passage 112 to the second refrigerant passage 114 are provided. You may make it prevent or suppress the leak of a refrigerant | coolant. Specifically, the depth of the large passage 158 may be increased, an O-ring may be disposed on the bottom side of the large passage 158, and the anti-vibration spring 148 may be disposed above the O-ring. In that case, the anti-vibration spring 148 can function as a stopper for locking the O-ring from above by the bottom surface of the folded portion.

  The expansion valve of the above embodiment is preferably applied to a refrigeration cycle that uses an alternative chlorofluorocarbon as a refrigerant, but the expansion valve of the present invention is applied to a refrigeration cycle that uses a refrigerant having a high operating pressure such as carbon dioxide. It is also possible. In that case, an external heat exchanger such as a gas cooler is arranged in the refrigeration cycle instead of the condenser. At this time, in order to supplement the strength of the diaphragm 128 that constitutes the power element 120, for example, a metal disc spring or the like may be arranged in an overlapping manner. Alternatively, a disc spring or the like may be arranged in place of the diaphragm 128.

  100 Expansion Valve, 102 Condenser, 104 Evaporator, 106 Compressor, 108 Receiver, 110 Car Air Conditioner, 112 First Refrigerant Passage, 114 Second Refrigerant Passage, 116 Body, 118 Valve Body, 120 Power Element, 122 Shaft, 124 Disc, 126 Screw hole, 128 Diaphragm, 130 Upper housing, 132 Lower housing, 134 Sealed space, 136 Sensitive greenhouse, 138 Connection path, 140 Spring, 142 Valve body receiver, 144 Through path, 146 Adjust screw, 148 Anti-vibration spring, 150 Large diameter part, 152 Small diameter part, 154 Abutable area, 156 Projection, 158 Large path, 160 Small path, 162 Burr, 164 Opposable area, 166 O-ring, B boundary.

Claims (5)

A body having a first refrigerant passage for passing the refrigerant flowing in through the heat exchanger toward the evaporator, and a second refrigerant passage for allowing the refrigerant returned from the evaporator to pass toward the compressor; ,
A driving unit that generates a driving force in accordance with the pressure and temperature of the refrigerant passing through the second refrigerant passage;
An operating rod penetrating the partition walls of the first and second refrigerant passages and being displaced by the driving force;
A valve body that is installed in the first refrigerant passage and opens and closes the first refrigerant passage according to displacement of the operating rod;
An anti-vibration spring interposed between the body and the actuating rod and contacting the actuating rod;
The actuating rod has a large-diameter portion and a small-diameter portion having an outer diameter smaller than the large-diameter portion, and in the section from the closed state of the first refrigerant passage to the maximum open state, the vibration isolation An expansion valve, wherein the spring abuts at the small diameter portion. The through-passage of the operating rod in the partition has a large passage for accommodating a vibration-proof spring and a small passage having an inner diameter smaller than that of the large passage,
The expansion valve according to claim 1, wherein a boundary between the small passage and the large passage faces the small diameter portion.   3. The expansion valve according to claim 1, wherein the operating rod is a bar-like member that is symmetrical in the longitudinal direction and has the small-diameter portion between two large-diameter portions.   The expansion valve according to any one of claims 1 to 3, wherein the surface of the small diameter portion is a rolled surface. The drive unit has a sealed space in which a gas that transmits a driving force to the operating rod by its expansion and contraction is sealed, and a temperature-sensitive room that houses a disk that transmits the temperature of the refrigerant to the sealed space.
5. The expansion valve according to claim 1, wherein a part of the disk protrudes into a connection path that connects the temperature-sensitive room and the second refrigerant passage.

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