JP2017172846A - Expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a driving property of a power element by rapidly discharging an unnecessary objects from an inside of the power element.SOLUTION: An expansion valve of the present invention includes: a first refrigerant passage through which a refrigerant flowed via a condenser passes toward an evaporator; and a second refrigerant passage through which a refrigerant returned from the evaporator passes toward a compressor. A power element 120 generates a driving force according to a pressure and temperature of the refrigerant which passes the second refrigerant passage. A shaft penetrates a partition wall of the first and second refrigerant passage, and displaces by the driving force. The first refrigerant passage opens and closes by the valve by the displacement of the shaft. A connection path 138 connecting the second refrigerant passage and the power element 120 has a tapered face 152 in which an opening on the side of the power element 120 is made larger.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an expansion valve, and more particularly to the structure of a connecting portion of a power element.

  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. An actuator (drive unit) called a power element is installed in the upper part of the second refrigerant passage. The power element displaces the shaft in accordance with the pressure of the refrigerant passing through the second refrigerant passage and the evaporation temperature. The shaft changes the opening of the valve body of the first refrigerant passage by the displacement (see Patent Document 1).

JP2013-242129A

  By fitting the power element into the opening in the upper part of the body of the expansion valve, the second refrigerant passage and the power element communicate with each other. A part of the refrigerant flowing through the second refrigerant passage flows into the power element from the opening. The power element generates a driving force according to the temperature and pressure of the refrigerant that has flowed in.

  In the power element, not only gas-phase refrigerant but also liquid-phase refrigerant and oil (lubricating oil) contained in the refrigerant enter the power element. Since liquid phase refrigerant and oil have a smaller time constant for heat transfer than gas phase refrigerant, if they stay in the power element, there is a possibility of causing hunting in which the valve section frequently opens and closes. For this reason, it is necessary to prevent liquid phase refrigerant and oil from staying in the vicinity of the power element.

  The present invention has been completed on the basis of recognition of the above problems by the present inventors, and its main purpose is to improve the drivability of the power element of the expansion valve, in particular, to quickly remove unwanted materials from the inside of the power element. It is to be discharged.

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 returning 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. And a valve body that is installed in the first refrigerant passage and opens and closes the first refrigerant passage according to the displacement of the operation rod.
The connecting path that connects the second refrigerant passage and the drive unit has an inclined part in which the opening on the drive unit side is enlarged.

  By making the inner wall surface of the connection path into a tapered shape, it becomes difficult for unwanted substances such as liquid refrigerant and oil to stay in the connection path. Such a configuration makes it easy to suppress hunting.

  According to the present invention, it becomes easy to stabilize the driving force of the power element in the expansion valve.

It is sectional drawing of the expansion valve in 1st Embodiment. In 1st Embodiment, it is an enlarged view of the area | region A of FIG. In a comparative example, it is an enlarged view of area A. In 1st Embodiment, it is an enlarged view (modified example) of the area | region A of FIG. It is sectional drawing of the expansion valve in 2nd Embodiment. In 2nd Embodiment, it is an enlarged view of the area | region A of FIG.

  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 alternative chlorofluorocarbon, and the refrigerant circulates through the compressor 106, the condenser 102 that functions 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 shaft 122 functions as an “operating rod” that controls the amount of refrigerant supplied from the condenser 102 to the evaporator 104. 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.

  The internal pressure of the sealed space 134 changes according to the gas saturation pressure. 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.

FIG. 2 is an enlarged view of region A in FIG. FIG. 3 is an enlarged view of region A in the comparative example.
As shown in FIG. 1, an opening is formed in the upper surface of the body 116, and the power element 120 is fixed to this opening. Since the lower part of the power element 120 is also opened, the sensitive room 136 communicates with the second refrigerant passage 114 via the connection path 138. A part of the refrigerant sent from the evaporator 104 enters the sensitive room 136 and changes the temperature of the disk 124.

  The refrigerant passing through the second refrigerant passage 114 includes not only a gas phase refrigerant but also a liquid phase refrigerant in an operation region where the degree of superheat is low. In addition, a small amount of lubricating oil contained in the refrigerant may also enter the power element 120 (the sensitive room 136). Liquid phase refrigerant and lubricating oil (hereinafter collectively referred to as “liquid”) have a smaller heat transfer time constant than gas phase refrigerant, and thus destabilize the temperature-sensitive function of the power element 120.

The connection path 138 in the comparative example has a cylindrical shape (see FIG. 3). Since a flat step surface 150 is formed in the opening portion on the power element 120 (lower housing 132) side in the horizontal direction, the liquid tends to stay here. On the other hand, the connecting path 138 in the first embodiment has a tapered surface 152 (inclined surface) formed in the opening on the power element 120 side (see FIG. 2). All of the inner surface of the connection path 138 may be formed as a tapered surface 152, or the tapered surface 152 may be formed only in a part (upper part) on the power element 120 side as shown in FIG. In FIG. 2, since the step surface 150 (surface perpendicular to the axial direction of the shaft 122: the axis vertical surface) as in the comparative example is not formed, even if the liquid enters the sensitive room 136, it does not stay there and the liquid does not stay there. 2 It becomes easy to be discharged into the refrigerant passage 114. The tapered surface 152 promotes the gravity drop of the liquid.
The inclination angle a of the tapered surface 152 with respect to the axis-perpendicular surface needs to be 5 degrees or more, and is preferably 15 degrees or more. In the present embodiment, the axis vertical plane is a horizontal plane.

  The opening of the power element 120 is circular. In FIG. 2, the opening diameter D2 on the power element 120 side (upper surface side) of the connecting path 138 is, in other words, the opening diameter D2 on the upper side of the connecting path 138 is larger than the opening diameter (inner diameter) D1 of the power element 120. Large (D2> D1). That is, the opening area on the upper side of the connection path 138 is larger than the opening area (lower opening area) of the power element 120. Since the upper opening area of the connection path 138 is larger than the lower surface of the disk 124, the refrigerant can easily touch the entire lower surface of the disk 124, and the evaporation temperature of the sensitive room 136 is easily transmitted to the disk 124.

When viewed from the second refrigerant passage 114, the connection passage 138 has a narrow inlet and a large outlet (power element 120 side opening). If the entrance is wide, there is a concern that the refrigerant flows excessively into the sensation greenhouse 136 and the temperature change of the sealed space 134 becomes too large. On the other hand, the wider the outlet, the easier it is to make the temperature and pressure of the entire lower surface of the disk 124 uniform.
The structure shown in FIG. 2 meets the three design requirements that the inlet of the connecting path 138 should not be excessively large, the outlet should be as large as possible, and liquid should not stay.

FIG. 4 is an enlarged view of a region A in a modification of the first embodiment.
In FIG. 4, the tapered surface 152 is formed on the upper portion of the connecting path 138, but the step surface 150 is formed on the upper end portion of the tapered surface 152. Also in FIG. 4, the upper opening diameter D <b> 2 of the connection path 138 is larger than the opening inner diameter D <b> 1 of the lower housing 132. Since the opening area on the upper side of the connection path 138 is larger than the opening area (lower opening area) of the power element 120, the liquid temperature is difficult to be transmitted to the disk 124 even if the liquid stays on the stepped surface 150. ing.

  The tapered surface 152 is desirably a smooth inclined surface, but at least the connection path 138 only needs to include an inclined portion capable of promoting the liquid gravity drop.

[Second Embodiment]
FIG. 5 is a cross-sectional view of the expansion valve 100 in the second embodiment. FIG. 6 is an enlarged view of region A in FIG.
The difference between the first embodiment and the second embodiment is the shape of the disk 124 accommodated in the power element 120. A part of the lower surface of the disk 124 in the second 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. As shown in FIG. 5, the disk 124 is in contact with the refrigerant on the side surface 170 in addition to the horizontal surfaces 168a and 168b parallel to the axial vertical surface.

  In particular, when the diameter of the power element 120 is reduced, the driving force of the power element 120 is reduced. One of the causes is that, as the diameter of the power element 120 is reduced, the diameter D3 of the temperature sensing surface (horizontal plane 168) of the disk 124 is reduced, and the contact area of the disk 124 with the refrigerant is reduced. Therefore, as in the second embodiment, a part of the disk 124 is protruded from the temperature-sensitive room 136 to the connection path 138 to bring the refrigerant into contact with not only the horizontal surface 168 but also the side surface 170, thereby controlling the evaporation temperature in the sealed space gas chamber. It is easy to convey to 134.

In the above, based on embodiment, it demonstrated centering on the shape of the expansion valve 100, especially the connection path 138 formed in the body 116. FIG.
According to the present embodiment, liquid components such as liquid refrigerant and oil that have entered the sensation greenhouse 136 from the connection path 138 are less likely to stay in the sensation greenhouse 136, so that the power element 120 can be driven stably.

  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 and the shaft 122 shown in FIG. 1 to prevent leakage of the refrigerant from the first refrigerant passage 112 to the second refrigerant passage 114. Or you may make it suppress.

  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 step surface, 152 taper surface, 166 O-ring.

Claims (2)

A body having a first refrigerant passage through which the refrigerant flowing in through the heat exchanger passes toward the evaporator, and a second refrigerant passage through which the refrigerant returning from the evaporator passes 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 expansion valve characterized in that a connecting path connecting the second refrigerant passage and the driving portion has an inclined portion in which an opening on the driving portion side is enlarged. The drive unit includes a sealed space in which a gas that transmits a driving force to the operating rod is sealed by expansion and contraction, a disk that stores a disk that transmits a temperature of a refrigerant to the sealed space, and is opened on the connection path side. Have
The expansion valve according to claim 1, wherein an opening area on the drive unit side of the connection path is larger than an opening area of the temperature sensitive room.

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