CN112303967A

CN112303967A - Expansion valve and refrigeration cycle system

Info

Publication number: CN112303967A
Application number: CN202010680476.XA
Authority: CN
Inventors: 高田裕正; 佐藤祐一; 当山雄一郎
Original assignee: Saginomiya Seisakusho Inc
Current assignee: Saginomiya Seisakusho Inc
Priority date: 2019-07-26
Filing date: 2020-07-15
Publication date: 2021-02-02
Also published as: JP2021021439A; JP7134146B2

Abstract

The invention provides an expansion valve and a refrigeration cycle system, which can inhibit the oscillation generation in a micro-opening area. The expansion valve is characterized by comprising a valve body (120) provided with a valve port (121), a needle valve (140) which increases and decreases the flow rate of the refrigerant by changing the opening degree of the needle valve (121) in the axial direction toward or away from the valve port (121), a drive element having an operation chamber and a diaphragm, and a temperature sensing unit, wherein the refrigerant passes through the secondary port at a predetermined leakage flow rate even in a valve-closed state in which the needle valve (140) is closest to the valve port (121), and an outer peripheral surface (142a) on the tip side of the needle valve (140) has a shape in which the inclination angle (theta 21) on the acute angle side with respect to the central axis (13a-1) of a connection plane (142a-1) on the outer peripheral surface (142a) increases toward the tip of the needle valve (140.

Description

Expansion valve and refrigeration cycle system

Technical Field

The present invention relates to an expansion valve that expands a refrigerant in a high-pressure state to a low-pressure state and passes through a valve port, and a refrigeration cycle including the expansion valve.

Background

Conventionally, there is known a thermal expansion valve in which a diaphragm is displaced in accordance with a change in internal pressure of an operation chamber that has received a change in temperature of an object to be cooled, and the opening degree of a valve port is changed in response to the displacement of the diaphragm, thereby changing the flow rate of a refrigerant (see, for example, patent document 1). In this case, when an electronic component such as a cpu (central Processing unit) is used as the object to be cooled, the temperature of the object to be cooled may be controlled to be, for example, 20 to 40 ℃ without depending on the amount of heat generated by the object to be cooled in order to suppress excessive heat generation and excessive cooling.

Documents of the prior art

Patent document 1: japanese patent laid-open publication No. 2003-302125

Here, in the above-described expansion valve, when the object to be cooled having a maximum load of 1000W generates heat at a small amount of heat of about 100W, for example, in order to precisely control the temperature of the object to be cooled, a small amount of refrigerant may flow through the valve port with a small opening degree, and the flow rate may be precisely controlled.

In the above-described small opening area, the pressure on the high-pressure side decreases as the valve port is opened, and the change in the pressure receiving area of the needle valve receiving the pressure from the refrigerant as the valve is opened tends to increase. Therefore, in the small opening area, the needle valve tends to oscillate to frequently approach or separate from the valve port, and it may be difficult to precisely control the temperature of the object to be cooled.

Disclosure of Invention

The present invention has been made in view of the above-described problems, and an object thereof is to provide an expansion valve and a refrigeration cycle system capable of suppressing the occurrence of hunting in a small opening degree region.

In order to solve the above-described problems, an expansion valve according to the present invention includes a primary port through which a refrigerant that cools an object to be cooled flows in a high-pressure state, a valve body provided with a valve port through which the refrigerant that has flowed into the primary port expands in a low-pressure state, a secondary port through which the refrigerant that has passed through the valve port flows out, a needle valve that has a tapered shape along an axial direction of the valve port and is provided so that a tip end side thereof can move in the axial direction toward the valve port, and that increases or decreases a flow rate of the refrigerant that has passed through the valve port by changing an opening degree of the valve port by approaching or separating the valve port in the axial direction, an operation chamber capable of changing an internal pressure, and a driving element that has a diaphragm that moves in the axial direction in accordance with a change in the internal pressure of the operation chamber and causes the needle valve to approach or separate from the valve port, And a temperature sensing unit that changes an internal pressure of the operation chamber in the drive element according to a change in temperature of the object to be cooled, wherein the refrigerant passes through the secondary port at a predetermined flow rate even in a valve-closed state in which the needle valve is closest to the valve port, and an outer peripheral surface of the needle valve on the tip end side has a shape in which an inclination angle of an acute angle side with respect to a connecting plane of the outer peripheral surface with respect to a central axis of the needle valve increases toward the tip end of the needle valve.

According to the expansion valve of the present invention, since the refrigerant flows at the leakage flow rate also in the valve-closed state, it is possible to suppress a pressure drop at the valve-opening timing from the valve-closed state and a drastic change in the pressure receiving area of the needle valve that receives the pressure from the refrigerant, which is caused by the valve opening. Further, the outer peripheral surface of the needle valve on the tip side has a shape in which the inclination angle of the connection plane on the acute angle side with respect to the central axis becomes larger toward the tip. According to this shape of the needle valve, when the needle valve is separated from the valve port after the valve is opened, the amount of change in the opening degree of the valve port corresponding to the gap between the outer peripheral surface on the tip end side and the valve port is suppressed to be small for a short time after the valve is opened, and increases as the separation amount increases. Since the amount of change in the opening is suppressed for a short time after the valve is opened, a pressure drop and a drastic change in the pressure receiving area can be suppressed even in a small opening region after the valve is opened. Therefore, the expansion valve according to the present invention can suppress the occurrence of hunting in a small opening region including the valve port when the valve is opened.

Here, in the expansion valve of the present invention, it is preferable that a gap corresponding to the leakage flow rate is opened between the valve port and the needle valve even in the valve-closed state.

According to this structure, the leakage flow rate can be effectively ensured by the gap between the valve port and the needle valve in the valve-closed state.

In this configuration, the valve port includes a through hole penetrating through a valve seat wall of the valve body that separates the primary port side and the secondary port side, and a leak groove that is recessed so as to obtain a groove area corresponding to the leak flow rate in a plan view with respect to the valve port and extends from the primary port side to the secondary port side, and a part of at least one of an inner peripheral surface of the through hole and an outer peripheral surface of the needle valve is preferably formed.

According to this configuration, the needle valve can be stably closed by bringing the needle valve into the seated state, and the leakage flow rate in the valve-closed state can be effectively ensured by the leakage groove. Further, by providing the leak groove, even if foreign matter mixed with the refrigerant flows into the valve port from the primary port side when the valve is opened, the foreign matter can be discharged to the secondary port side through the leak groove, and therefore, clogging of the foreign matter in the valve port region in the small opening region can be suppressed.

In this configuration, the leakage groove may have a plurality of rows of groove portions each having a total groove area equal to an area corresponding to the leakage flow rate.

According to this configuration, since the refrigerant flows through the plurality of groove portions, a sufficient leakage flow rate can be ensured even when it is difficult to form a leakage groove having a sufficient groove area from the one-row groove.

In the expansion valve of the present invention, it is preferable that a through hole penetrating through a valve seat wall that separates the primary port side and the secondary port side in the valve main body is provided as the valve port, and a leak port penetrating through the valve seat wall so as to obtain a port area corresponding to the leak flow rate in a plan view with respect to the valve port is provided, the needle valve has a tapered shape that is thinner than the valve port, has a tip needle portion that is housed in the valve port at least on a root side in the valve-closed state, and has a seating portion that protrudes from the root of the tip needle portion in a tip-wide shape so as to have a diameter larger than an inner diameter of the valve port from a root portion thereof and that becomes a seating state in which a peripheral surface thereof abuts against an edge of the valve port in the valve-closed state, and in the plan view, an area of a gap that is opened annularly between an inner peripheral surface of the valve port and the root portion of the tip needle portion is smaller than the port area.

According to this configuration, the needle valve can be stably closed by the seating state, and the leakage flow rate in the valve-closed state can be effectively ensured by the leakage port. In this configuration, immediately after the valve port is opened, the refrigerant passes through the valve port by an amount corresponding to the gap area between the inner peripheral surface of the valve port and the root of the distal needle portion in the needle valve, which gap area is opened annularly. In this case, since the clearance area is smaller than the port area of the leakage port, the change in the flow rate of the refrigerant immediately after the valve is opened can be effectively suppressed. That is, according to this configuration, it is possible to more effectively suppress the occurrence of oscillation in the small opening region including the valve port when the valve is opened.

In the expansion valve of the present invention, the valve port includes a through hole penetrating through a valve seat wall of the valve main body that separates the primary port side and the secondary port side, and a leak groove that is recessed so as to obtain a groove area corresponding to the leak flow rate in a plan view with respect to the valve port and extends from the primary port side to the secondary port side, at least a part of an inner peripheral surface of the through hole and an outer peripheral surface of the needle valve, the needle valve has a tapered shape that is thinner than the through hole, and includes a tip needle portion that is housed in the through hole in at least a part of a root side in the closed valve state, and a seating portion that protrudes in a tip width shape from a root of the tip needle portion so as to be larger than an inner diameter of the through hole and has a peripheral surface that abuts against an edge of the through hole in the closed valve state, in the above plan view, it is preferable that a gap area which is annularly opened between the inner peripheral surface of the through hole and the root portion of the distal end needle portion when the leak groove is not provided in the closed valve state is smaller than the groove area.

According to this configuration, the needle valve can be stably closed by bringing the needle valve into the seated state, and the leakage flow rate in the valve-closed state can be effectively ensured by the leakage groove. In this configuration, immediately after the valve port is opened, the refrigerant passes through the valve port by an amount corresponding to the gap area of the annular opening between the inner peripheral surface of the through hole in the valve port and the root of the distal needle portion in the needle valve. In this case, since the gap area is smaller than the groove area of the leak groove, the change in the flow rate of the refrigerant immediately after the valve is opened can be effectively suppressed. That is, the structure in which the leak groove is provided in the valve port is also the same as the above-described structure in which the leak port is provided in the valve main body, and thus, the occurrence of hunting in the small opening region including the valve port when the valve is opened can be more effectively suppressed.

In this configuration, the leakage groove may have a plurality of groove portions each having an area corresponding to the leakage flow rate as a sum of groove areas.

According to this configuration, since the refrigerant flows through the plurality of groove portions, a sufficient leakage flow rate can be ensured even when it is difficult to form a sufficient groove area by one groove.

In order to solve the above problem, a refrigeration cycle system according to the present invention includes a compressor for compressing a refrigerant for cooling an object to be cooled, a condenser for condensing the compressed refrigerant, an expansion valve according to the present invention for expanding and decompressing the condensed refrigerant, and an evaporator for absorbing heat generated by the object to be cooled in the decompressed refrigerant and evaporating the refrigerant.

According to the refrigeration cycle system of the present invention, since the expansion valve of the present invention is used, the occurrence of hunting in the micro-opening region of the expansion valve can be suppressed.

The effects of the present invention are as follows.

The expansion valve and the refrigeration cycle system according to the present invention can suppress the occurrence of hunting in the micro-opening region.

Drawings

Fig. 1 is a schematic view showing a refrigeration cycle system according to a first embodiment of the present invention.

Fig. 2 is a view showing the expansion valve shown in fig. 1.

Fig. 3 is a schematic diagram showing a structure for suppressing oscillation when the needle valve shown in fig. 2 is slightly opened.

Fig. 4 is a schematic diagram showing a change in valve opening area of the valve port when the needle valve is separated from the valve port from the closed valve state to the open valve state.

Fig. 5 is a graph illustrating a change in the valve opening area of the valve port when the needle valve is separated from the valve port from the valve-closed state to the valve-open state, and a change in the valve opening area with respect to the evaporation load in the evaporator corresponding to the amount of heat absorbed from the object to be cooled.

Fig. 6 is a schematic view showing a needle and a valve seat wall in a second embodiment.

Fig. 7 is a schematic diagram showing a change in the positional relationship between the needle and the valve port when the needle valve is separated from the valve port from the valve-closed state to the valve-open state.

Fig. 8 is a graph depicting the change in the sum of the port area of the vent port and the valve opening area of the valve port when the positional relationship of the needle and the valve port changes in the manner shown in fig. 7.

Fig. 9 is a schematic view showing a needle and a valve seat wall in the third embodiment.

Fig. 10 is a schematic view showing a needle in the fourth embodiment.

Fig. 11 is a schematic view showing a needle in the fifth embodiment.

Fig. 12 is a schematic view showing a needle in a sixth embodiment.

In the figure: 1-a refrigeration cycle system, 11-a compressor, 12-a condenser, 13-an expansion valve, 13 a-a valve assembly, 13a-1, 23a-1, 43 a-1-a central shaft, 13 b-a temperature sensing part, 14-an evaporator, 110-a primary port, 111-a first coil spring, 120, 220, 320-a valve body, 121, 221, 321-a valve port, 122, 222, 322-a valve seat wall, 130-a secondary port, 140, 240-a needle valve, 142, 242, 442, 542, 642-a needle, 142a, 242a-2, 242b-1, 442a-1, 442b-1, 542a-1, 542b-1, 642a-1, 642-an outer peripheral surface, 142a-1, 242 a-1-a connection plane, 150-a driving element, 153-a diaphragm, 157-an operation chamber, 221a, 321 a-1-a rim, 223-a leakage port, 242a, 442a, 542a, 642 a-the tip needle portion, 242 a-1-the base, 242b, 442b, 542b, 642 b-the seat portion, 321 a-the through hole, 321 b-the leakage groove, Tg-the cooled object, θ 11, θ 21, θ 22, θ 41-the inclination angle, S21, S31-the gap area, Sb 21-the port area, Sb 31-the groove area, Ga 11-the micro gap, Ga 12-the gap, D11-the axial direction, D111-the valve opening direction.

Detailed Description

The expansion valve and the refrigeration cycle according to an embodiment of the present invention will be described below. First, a first embodiment will be described.

The refrigeration cycle system 1 shown in fig. 1 is a system for cooling an object to be cooled Tg by absorbing heat generated by the object to be cooled Tg such as a CPU in a refrigerant. The refrigeration cycle 1 includes a compressor 11 of refrigerant, a condenser 12, an expansion valve 13, and an evaporator 14.

The compressor 11 compresses the refrigerant that absorbs heat of the cooled object Tg. The condenser 12 condenses the compressed refrigerant and flows the condensed refrigerant to the expansion valve 13.

The expansion valve 13 expands the condensed refrigerant, reduces the pressure of the refrigerant, and flows toward the object to be cooled Tg. The expansion valve 13 includes a valve assembly 13a through which the refrigerant passes, and a temperature sensing unit 13b that senses the temperature of the refrigerant immediately after the heat of the object to be cooled Tg is absorbed. In fig. 1, the internal structure of the valve assembly 13a in the expansion valve 13 is shown in a cross-sectional view in a visually recognizable manner. The expansion valve 13 is a temperature type expansion valve that increases or decreases the flow rate of the refrigerant passing through the valve assembly 13a in accordance with a change in the temperature of the refrigerant sensed by the temperature sensing unit 13b, that is, a change in the temperature of the object to be cooled Tg. The expansion valve 13 will be described in detail later.

The evaporator 14 is disposed in the vicinity of the object to be cooled Tg, and absorbs heat generated by the object to be cooled Tg in the refrigerant decompressed by the expansion valve 13 to evaporate the refrigerant. The temperature sensing unit 13b of the expansion valve 13 is disposed near the outlet of the refrigerant in the evaporator 14.

In the refrigeration cycle 1, a refrigerant circulates through the compressor 11, the condenser 12, the expansion valve 13, and the evaporator 14 in this order, and the evaporator 14 absorbs heat of the object to be cooled Tg and cools the object.

Fig. 2 is a view showing the expansion valve shown in fig. 1. In fig. 2, the valve assembly 13a shown in a sectional view is shown enlarged together with the temperature sensing unit 13b as in fig. 1.

The expansion valve 13 includes the valve assembly 13a and the temperature sensing unit 13b as described above, and the valve assembly 13a includes the primary port 110, the valve body 120, the secondary port 130, the needle valve 140, and the driving element 150.

The primary port 110 is a cylindrical portion into which the refrigerant condensed in the condenser 12 flows in a high-pressure state, and has one end side serving as an inlet of the refrigerant and the other end side connected to the valve body 120. The primary port 110 is coupled to the valve main body 120 such that the central axis thereof coincides with the central axis 13a-1 of the valve assembly 13 a. The other end of the primary port 110 houses a first coil spring 111 that urges the needle valve 140 toward a valve port 121 described later. Further, an adjusting portion 112 that adjusts the urging force generated by the first coil spring 111 is disposed in the middle of the primary port 111. The adjusting portion 112 is disposed at a position where the first coil spring 111 is compressed so as to obtain a desired biasing force in the axial direction of the primary port 110, and is fixed by pressure contact inside the primary port 110 at the adjusting position. The adjusting portion 112 is provided with a flow path 112a for flowing the refrigerant flowing in from one end side of the primary port 110 to the other end side.

The valve main body 120 has a valve seat wall 122 provided with a cylindrical valve port 121 through which a high-pressure refrigerant flowing into the primary port expands to a low-pressure state. The valve main body 120 is provided with a cylindrical high-pressure space 123 formed coaxially with the central axis 13a-1 of the valve element 13a, and a low-pressure space 124 formed orthogonally to the central axis 13a-1, both of which are partitioned by a valve seat wall 122. The valve port 121 is formed through the valve seat wall 122 in a cylindrical shape coaxial with the center axis 13a-1 of the valve element 13a in the axial direction D11 of the center axis 13 a-1. In the high-pressure space 123, one end side of the primary port 110 is connected to the inlet side thereof, and the needle valve 140 is housed in the high-pressure space 123 so that a part thereof enters one end side of the primary port 110. Further, the low-pressure space 124 is connected at its outlet side to one end side of the secondary port 130. Further, the drive element 150, which moves the needle valve 140 housed in the high-pressure space 123 in the axial direction D11 and moves closer to or away from the valve port 121, is coupled to the end portion of the valve main body 120 opposite to the primary port 110 in the axial direction D11. When the needle valve 140 is separated from the valve port 121 by the drive element 150 to open the valve port 121, the refrigerant in the high-pressure space 123 expands to a low-pressure state and flows into the low-pressure space 124 through the valve port 121.

The secondary port 130 is a cylindrical portion that allows the refrigerant flowing into the low-pressure space 124 through the valve port 121 to flow out to the evaporator 14 shown in fig. 1, and one end side thereof is connected to the low-pressure space 124 of the valve main body 120. In the present embodiment, the secondary port 130 is coupled to the valve main body 120 so as to extend in a direction orthogonal to the extending direction of the primary port 110.

The needle valve 140 is a portion that changes its opening degree by approaching or separating from the valve port 121 in the axial direction D11 of the valve port 121 to increase or decrease the flow rate of the refrigerant passing through the valve port 121, and includes a bottomed cylindrical portion 141 and a needle 142. The bottomed cylindrical portion 141 is housed in the high-pressure space 123 such that the bottom wall 141a is movable in the axial direction D11 toward the valve port 121 so that the edge of the opening side thereof enters the primary port 110 and receives the biasing force generated by the first coil spring 111. A needle 142 is provided upright on the bottom wall 141a so as to protrude toward the valve port 121, and a flow path 141b for allowing the refrigerant from the primary port 110 to flow into the high-pressure space 123 is formed through the bottom wall 141 a. The needle 142 has a tapered shape in the axial direction D11 of the valve port 121. The needle valve 140 is housed in the high-pressure space 123 so that the tip end side of the needle 142 is movable in the axial direction D11 toward the valve port 121, and is provided in the valve main body 120.

The driving element 150 includes an upper cover 151, a lower cover 152, a diaphragm 153, a contact member 154, a coupling rod 155, and a second coil spring 156. The upper cover 151, the lower cover 152, and the diaphragm 153 have circular shapes having substantially the same diameter in a plan view from the axial direction D11, and the outer edge portion of the diaphragm 153 is sandwiched between the upper cover 151 and the lower cover 152 and welded thereto. At this time, the center portion of the upper cover 151 is formed to bulge in a direction away from the diaphragm 153, and a space defined by the center portion and the diaphragm 153 serves as an operation chamber 157 in which the internal pressure can be changed. The operation chamber 157 is connected to the temperature sensing unit 13b through a capillary tube 13c, and a seal gas is sealed in the operation chamber 157 and the temperature sensing unit 13 b. The sealing gas may be the same gas as the refrigerant evaporated in the evaporator 14, may be another gas having the same or similar temperature and pressure characteristics as the refrigerant, or may be a mixture of inert gases. The temperature of the seal gas in the temperature sensing unit 13b changes in accordance with the outlet-side temperature of the evaporator 14, and the internal pressure of the temperature sensing unit 13b changes. Accordingly, the internal pressure of the operation chamber 157 is also changed by the capillary 13c, and the diaphragm 153 is displaced in the axial direction D11 by the change in the internal pressure.

The lower cover 152 is formed to have a central portion bulging in a direction opposite to the upper cover 151. The lower cover 152 is coupled to the valve main body 120 in a state where the end portion of the valve main body 120 opposite to the primary port 110 enters the through hole 152a formed in the central portion. The contact piece 154 is provided on the surface of the diaphragm 153 on the lower cover 152 side, and the end of the connection rod 155 on the opposite side to the valve port 121 is fixed by pressure bonding or the like. With this configuration, displacement of the diaphragm 153 in the axial direction D11 is transmitted to the connecting rod 155 via the contact piece 154.

The connecting rod 155 is a portion that transmits the displacement of the diaphragm 153 transmitted as described above to the needle 142 of the needle valve 140 and moves the needle 142 in the axial direction D11, and includes a round rod portion 155a, a conical portion 155b, and a tip end contact portion 155 c. The round bar portion 155a is a columnar portion having one end fixed to the contact piece 154. The conical portion 155b is a portion that is provided at the end of the round rod portion 155a opposite to the contact piece 154 and that is tapered to a diameter slightly smaller than the valve port 121. The distal end contact portion 155c is a portion that protrudes from the distal end of the conical portion 155b in a cylindrical shape having a diameter slightly smaller than the valve port 121, and the distal end thereof enters the valve port 121 and contacts the needle 142 of the needle valve 140.

The valve main body 120 is provided with a guide portion 125 at an end opposite to the primary port 110, which guides and holds the connecting rod 155 in the axial direction D11 by passing the round rod portion 155a of the connecting rod 155 through the through hole 125 a. The housing portion 126 of the second coil spring 156 is formed so as to surround the guide portion 125 around the central axis 13 a-1. The second coil spring 156 urges the diaphragm 153 toward the upper cover 151 in the axial direction D11 via the contact piece 154.

When the temperature of the object to be cooled Tg rises and the temperature of the seal gas in the temperature sensing unit 13b rises, the temperature of the seal gas in the operation chamber 157 of the driving element 150 connected to the temperature sensing unit 13b through the capillary 13c also rises and the internal pressure thereof rises. When the working force applied to the diaphragm 153 by the internal pressure of the operation chamber 157 exceeds the sum of the biasing force of the first coil spring 111 of the primary port 110, the biasing force of the second coil spring 156 of the housing portion 126, and the biasing force applied to the diaphragm 153 by the internal pressure of the housing portion 126, the diaphragm 153 is displaced in the direction away from the upper cover 151. Then, the connection rod 155 receives the displacement of the diaphragm 153 and moves toward the valve port 121, and presses the needle 142 of the needle valve 140 against the operating force of the first coil spring 111 to open the valve port 121. This increases the flow rate of the refrigerant for cooling the object to be cooled Tg, thereby improving the cooling effect on the object to be cooled Tg. Further, since the housing portion 126 communicates with the low-pressure space 124 (and the secondary port 130), the internal pressure of the housing portion 126 is the same pressure as the low-pressure space 124 (and the secondary port 130).

On the other hand, when the temperature of the object to be cooled Tg decreases and the temperature of the seal gas in the temperature sensing unit 13b decreases, the temperature of the seal gas in the operation chamber 157 also decreases and the internal pressure thereof decreases. When the biasing force that biases the diaphragm 153 by the internal pressure of the operation chamber 157 is reduced to be lower than the total of the biasing forces, the diaphragm 153 is displaced toward the upper cover 151. Then, the connecting rod 155 is moved in a direction away from the valve port 121 by the displacement of the diaphragm 153, and pushes up the needle 142 of the needle valve 140 by the biasing force of the first coil spring 111 to close the valve port 121. This reduces the flow rate of the coolant for cooling the object to be cooled Tg, and suppresses the cooling effect on the object to be cooled Tg.

Here, in the present embodiment, the needle valve 140 is configured as follows in order to suppress the oscillation generation at the time of the minute valve opening.

Fig. 3 is a schematic view of a structure for suppressing oscillation when a valve is slightly opened in the needle valve shown in fig. 2. In fig. 3, the needle 142 of the needle valve 140 is shown in an enlarged view together with the valve port 121 of the valve seat wall 122 in the valve body 120.

In the present embodiment, first, the needle valve 140 is configured such that the refrigerant passes through the secondary port 130 (i.e., the low-pressure space 124) at a predetermined leakage flow rate even in a valve-closed state in which the needle valve 140 is closest to the valve port 121. That is, the movement of the needle valve 140 in the axial direction D11 in the interior of the high-pressure space 123 is restricted by a not-shown restrictor so that the small gap Ga11 is opened between the outer peripheral surface 142a of the needle 142 and the inner peripheral surface 121a of the valve port 121 in the valve-closed state.

The outer peripheral surface 142a of the needle 142 of the needle valve 140 has a bell-shaped shape in which the inclination angle θ 11 on the acute angle side with respect to the central axis 13a-1 of the connection plane 142a-1 of the outer peripheral surface 142a increases toward the tip of the needle 142. The valve opening area of the valve port 121 that determines the flow rate of the refrigerant changes as follows as the needle 140 moves away from the valve port 121 in the valve opening direction D111 from the closed-valve state to the open-valve state due to the aforementioned bell-shaped shape of the small gap Ga11 and the needle 142 in the closed-valve state.

Fig. 4 is a schematic diagram showing a change in valve opening area of the valve port when the needle valve is separated from the valve port from the closed valve state to the open valve state. Fig. 5 is a graph illustrating a change in the valve opening area of the valve port when the needle valve is separated from the valve port from the closed state to the open state, and a change in the valve opening area with respect to the evaporation load in the evaporator corresponding to the amount of heat absorbed from the object to be cooled.

The evaporation load in the evaporator 14 is small, and the valve closed state in which the needle valve 140 is closest to the valve port 121 is achieved while the biasing force applied to the diaphragm 153 by the internal pressure of the operation chamber 157 is lower than the sum of the biasing forces of the first coil spring 111 and the second coil spring 156 and the biasing force applied to the diaphragm 153 by the internal pressure of the housing portion 126. This state is the leakage region T11 in which the refrigerant flows through the minute gap Ga11 between the needle 142 and the valve port 121 at a leakage flow rate corresponding to the valve opening area in the minute gap Ga 11.

When the evaporation load increases and the biasing force applied to the diaphragm 153 by the internal pressure of the operation chamber 157 exceeds the total of the biasing forces generated by the first coil spring 111 and the like, the tip end contact portion 155c of the connection rod 155 receives the displacement of the diaphragm 153 and presses the needle 142 in the valve opening direction D111 to open the valve port 121. Thereafter, the gap Ga12 between the needle 142 and the valve port 121, that is, the valve opening area, expands with an increase in the evaporation load, and becomes the valve opening region T12 in which the flow rate of the refrigerant increases. At this time, the change in the valve opening area when the valve moves from the leakage region T11 to the valve opening region T12 is only the gap Ga12 expanding from the state in which the small gap Ga11 is already opened in the leakage region T11, and therefore, the change is substantially seamless in which a drastic change can be suppressed. This can suppress a transition from the leakage region T11 to the valve opening region T12, that is, a drastic pressure drop in the high-pressure space 123 accompanying the valve opening, and a drastic change in the pressure receiving area of the needle 142 receiving the pressure from the refrigerant accompanying the valve opening.

Further, the needle 142 has a bell-shaped outer peripheral surface 142a in which the inclination angle θ 11 of the connection plane 142a-1 increases toward the tip. Therefore, after the transition to the valve opening region T12, the amount of change in the valve opening area corresponding to the gap Ga12 between the needle 142 and the valve port 121 is slightly suppressed after the transition, the evaporation load further increases, and the evaporation load gradually increases as the amount of movement of the needle 142 increases. In this way, since the valve opening area, that is, the amount of change in the opening degree of the valve port 121 in the valve opening region T12 can be suppressed, a pressure drop and a drastic change in the pressure receiving area can be suppressed even in the valve opening region T12. Therefore, according to the expansion valve 13 of the present embodiment and the refrigeration cycle 1 including the expansion valve, it is possible to suppress the occurrence of hunting in the fine opening region including the valve port 121 when the valve is opened.

In the present embodiment, the minute gap Ga11 is formed between the valve port 121 and the needle 142 of the needle valve 140 even in the valve-closed state. With this configuration, a desired leakage flow rate in the valve-closed state can be effectively ensured.

Next, a second embodiment will be described. The needle shape and the valve seat wall provided with the valve port in the needle valve of the second embodiment are different from those of the first embodiment. Hereinafter, the second embodiment will be described with a focus on differences from the first embodiment. On the other hand, the overall configurations of the refrigeration cycle and the expansion valve, which are the same as those of the first embodiment, are not shown or described. In the following description, the components of the refrigeration cycle 1 shown in fig. 1 and the components of the expansion valve 13 shown in fig. 2 are referred to as appropriate.

In the present embodiment, two through holes having the size of the valve port 221 and the leakage port 223 are provided in the valve seat wall 222 of the valve main body 220. The valve port 221 is a through hole that penetrates the valve seat wall 222 from the primary port 110 side to the secondary port 130 side. The leakage port 223 is a through hole that penetrates the valve seat wall 222 from the primary port 110 side to the secondary port 130 side so as to obtain a port area Sb21 corresponding to the leakage flow rate in a plan view of the valve port 222.

The needle 242 of the needle valve 240 includes a distal needle portion 242a and a seating portion 242 b. The distal needle portion 242a has a tapered shape smaller than the valve port 221, and at least a part of the root portion 242a-1 side is accommodated in the valve port 221 in the valve-closed state. In the present embodiment, the outer peripheral surface 242a-2 of the distal end needle portion 242a has a bell-shaped configuration in which the inclination angle θ 21 on the acute angle side with respect to the central axis 23a-1 with respect to the connecting plane 242a-3 of the outer peripheral surface 242a-2 becomes larger toward the distal end. The seating portion 242b is a portion that protrudes from the root portion 242a-1 of the distal needle portion 242a in a wide end shape so as to have a diameter larger than the inner diameter of the valve port 221, and whose outer peripheral surface 242b-1 abuts against the rim 221 of the valve port 221 in a seated state in a valve closed state. In the present embodiment, the outer peripheral surface 242b-1 of the seating portion 242b is formed in a conical surface shape that opens with a constant degree of accuracy with respect to the acute-angle-side inclination angle θ 22 of the outer peripheral surface 242b-1 of the central axis 23 a-1.

In a plan view of the valve port 221, a gap area S21 annularly opened between the inner peripheral surface 221a of the valve port 221 and the root portion 242a-1 of the distal end needle portion 242a in the valve-closed state is smaller than a port area Sb21 of the leakage port 223.

In the second embodiment described above, as the needle valve 240 moves away from the valve port 221 from the valve-closed state to the valve-open state, the sum of the port area Sb21 of the leak port 223 and the valve opening area of the valve port 221 changes as follows.

Fig. 7 is a schematic diagram showing a change in the positional relationship between the needle and the valve port when the needle valve is separated from the valve port from the valve-closed state to the valve-open state. In fig. 7, the same reference numerals as in fig. 2 are given to the distal end contact portion 155c of the connecting rod 155 similar to that of the first embodiment. Fig. 8 is a graph illustrating a change in the sum of the port area of the leak port and the valve opening area of the valve port when the positional relationship between the needle and the valve port changes as illustrated in fig. 7.

The evaporation load in the evaporator 14 is small and the valve-closed state is achieved while the biasing force applied to the diaphragm 153 by the internal pressure of the operation chamber 157 is lower than the sum of the biasing forces of the first coil spring 111 and the second coil spring 156 and the biasing force applied to the diaphragm 153 by the internal pressure of the housing portion 126. In the present embodiment, the seating portion 242b of the needle 242 of the needle valve 240 is seated on the rim 221a of the valve port 221 in the valve-closed state. This state is a leakage region T21 in which the refrigerant flows through the leakage port 223 at a leakage flow rate corresponding to the port area Sb21 of the leakage port 223.

When the evaporation load increases and the biasing force applied to the diaphragm 153 by the internal pressure of the operation chamber 157 exceeds the total of the biasing forces generated by the first coil spring 111 and the like, the tip end contact portion 155c of the connection rod 155 pushes down the needle 242 by the displacement of the diaphragm 153 to open the valve port 221. Thus, a flow rate corresponding to the valve opening area of the valve port 221 is added to the leakage flow rate corresponding to the port area Sb21 passing through the leakage port 223, and the valve opening area, that is, the additional flow rate, is gradually increased as the needle 242 is pushed down. Here, a constant period immediately after the valve opening is completed passes through the conical outer peripheral surface 242b-1 of the seating portion 242b, the root portion 242a-1 of the tip needle portion 242a, and the bell-shaped outer peripheral surface 242a-2 of the tip needle portion 242a in this order in the vicinity of the edge 221a of the valve port 221. In this period, as the valve opening area of the valve port 221 increases, the linear increase in the gap between the conical outer peripheral surface 242b-1 of the seating portion 242b and the edge 221a of the valve port 221 becomes the dominant transition region T22.

When the evaporation load further increases and the needle 242 is further pushed down, the increase in the gap between the bell-shaped outer peripheral surface 242a-2 of the tip needle portion 242a and the edge 221a of the valve port 221 shifts to the dominant valve opening region T23 while the valve opening area of the valve port 221 increases. The increase in the valve opening area in the valve opening region T23 is suppressed to be small after the change amount is shifted, and is an increasing form that gradually increases as the movement amount of the needle 242 increases.

According to the second embodiment described above, the needle 242 of the needle valve 240 is brought into the seated state, whereby the valve can be stably closed, and the leakage flow rate in the closed state can be effectively ensured by the leakage port 223. In addition, in the present embodiment, a drastic pressure drop in the high-pressure space 123 accompanying a transition to the transition region T22 immediately after the valve is opened from the leakage region T21 (i.e., the valve is closed), and a drastic change in the pressure receiving area of the needle 242 receiving the pressure from the refrigerant accompanying the valve opening can be suppressed. Further, at the transition from the transition region T22 to the valve opening region T23 from the transition region T22, the increase in the valve opening area in the valve opening region T23 is in an increasing form in which the valve opening area gradually increases with the movement of the needle 242, and therefore, even here, a rapid pressure decrease and a rapid change in the pressure receiving area can be suppressed. Therefore, as in the first embodiment, the present embodiment can also suppress the occurrence of oscillation in the small opening region including the valve port 221 when the valve is opened.

In the present embodiment, the leakage port 223 having the port area Sb21 corresponding to the leakage flow rate is provided in the valve seat wall 222, and the needle 242 of the needle valve 240 has a bell-shaped distal needle portion 242a and a wide-end seating portion 242 b. The gap area S21 annularly opened between the inner peripheral surface of the valve port 221 and the root 242a-1 of the distal needle 242a in the closed state is smaller than the port area Sb 21.

In this configuration, immediately after the valve port 221 is opened, the refrigerant passes through the valve port 221 by an amount corresponding to the annular gap area S21. At this time, since the gap area S21 is smaller than the port area Sb21 of the leakage port 223, the change in the flow rate of the refrigerant immediately after the valve is opened can be effectively suppressed. That is, according to this configuration, the oscillation generation in the fine opening region including the valve port 221 when the valve is opened can be more effectively suppressed.

Next, a third embodiment will be described. This third embodiment is a modification of the second embodiment. The third embodiment differs from the second embodiment in that a structure is provided instead of the leakage port 223. Hereinafter, the third embodiment will be described with a focus on the difference from the second embodiment. On the other hand, as in the second embodiment, the overall configuration of the refrigeration cycle and the expansion valve is not shown or described. In the following description, reference is also made to the components of the refrigeration cycle 1 shown in fig. 1 and the components of the expansion valve 13 shown in fig. 2 as appropriate.

Fig. 9 is a schematic view showing a needle and a valve seat wall in the third embodiment. In fig. 9, the same components as those of the second embodiment shown in fig. 6 are denoted by the same reference numerals as those of fig. 6, and redundant description of these same components will be omitted below.

In the present embodiment, the valve port 321 provided in the valve seat wall 322 of the valve body 320 includes a through hole 321a and a leakage groove 321 b. The through hole 321a corresponds to the valve port 121 of the first embodiment and the valve port 221 of the second embodiment, and penetrates the valve seat wall 322 from the primary port 110 side to the secondary port 130 side. The leakage groove 321b is a groove in which a part of the inner peripheral surface 321a-2 of the through hole 321a is recessed so as to obtain a groove area Sb31 corresponding to a desired leakage flow rate in a plan view of the valve port 321, and extends from the primary port 110 side to the secondary port 130 side.

The seating portion 242b of the needle 242 of the needle valve 240 is in a seating state in which the conical outer peripheral surface 242b-1 thereof abuts against the edge 321a-1 of the through hole 321a of the valve port 321 in the valve-closed state. In the valve-closed state, the leakage groove 321b forms a gap that is opened between the valve port 321 and the needle valve 240 according to the leakage flow rate, and the refrigerant of the leakage flow rate flows into the low-pressure space 124 through the leakage groove 321 b.

In the present embodiment, when the leak groove 321b is provided, the gap area S31 is opened in an annular shape in a closed state between the inner peripheral surface of the through hole 31a and the root portion 242a-1 of the distal needle portion 242a in a plan view of the valve port 321. The gap area S31 is smaller than the groove area Sb31 of the leakage groove 321 b.

In the third embodiment described above, as in the second embodiment, the needle 242 of the needle valve 240 is brought into a seated state, whereby the valve can be stably closed, and the occurrence of hunting in a small opening region including the valve port 321 when the valve is opened can be suppressed.

In the present embodiment, the gap area S31 annularly opened between the inner peripheral surface 321a-2 of the through hole 321a of the valve port 321 and the root 242a-1 of the needle tip 242a in the closed state is smaller than the groove area Sb31 of the leakage groove 321 b. Therefore, the change in the flow rate of the refrigerant immediately after the valve is opened can be effectively suppressed. That is, the structure in which the leakage groove 321b is provided in the valve port 321 is also effective in suppressing the generation of the oscillation as in the second embodiment in which the leakage port 223 is provided in the valve seat wall 222. Further, by providing the leakage groove 321b, even if foreign matter mixed in the refrigerant flows into the valve port 321 from the primary port 110 side at the time of opening the valve, the foreign matter is discharged to the secondary port 130 side through the leakage groove 321 b. This also suppresses clogging of foreign matter in the valve port 321 in the small opening region.

In the third embodiment described above, the leakage groove 321b formed of a single row of grooves is exemplified, but the leakage groove for obtaining the leakage flow rate may be a modified example of a structure having a plurality of rows of groove portions. In this modification, the sum of the groove areas of the groove portions of the plurality of rows of the leak groove is an area corresponding to the leak flow rate. According to this modification, since the refrigerant flows through the groove portions in the plurality of rows, a sufficient leakage flow rate can be ensured even when it is difficult to form a leakage groove having a sufficient groove area from the groove portion in one row.

Next, the fourth to sixth embodiments will be described with reference to the drawings of fig. 10 to 12. Each of the fourth to sixth embodiments is a modification of the needle with a seat portion. Hereinafter, the fourth to sixth embodiments will be described focusing on the needle. On the other hand, the overall configurations of the refrigeration cycle and the expansion valve are not shown or described. In the following description, the components of the refrigeration cycle 1 shown in fig. 1 and the components of the expansion valve 13 shown in fig. 2 are also referred to as appropriate.

Fig. 10 is a schematic view showing a needle in the fourth embodiment.

The needle 442 shown in fig. 10 includes a distal end needle portion 442a having an outer peripheral surface 442a-1 formed by connecting conical surfaces 442a-2 in multiple stages, and a seating portion 442b having a conical outer peripheral surface 442 b-1. The stepped conical surfaces 442a-2 constituting the outer peripheral surface 442a-1 of the tip needle portion 442a are tapered toward the tip. Further, the inclination angle θ 41 on the acute angle side of the conical surface 442a-2 with respect to the central axis 43a-1 is larger as the distance from the tip end is larger.

The needle 442 according to the fourth embodiment also provides the same effects as those of the needles 242 according to the second and third embodiments in which the tip needle portion 242a includes the bell-shaped outer peripheral surface 242 a-2. That is, when the opening degree corresponding to the gap between the outer peripheral surface 442a-1 of the needle tip portion 442a and the valve port 121 increases, the amount of change in the opening degree is suppressed to be small after the opening is completed, and gradually increases as the amount of movement of the needle tip portion 442a increases. This can suppress the pressure drop and the abrupt change in the pressure receiving area, thereby suppressing the occurrence of the oscillation.

Fig. 11 is a schematic view showing a needle in the fifth embodiment.

The needle 542 shown in fig. 11 includes a distal needle portion 542a having an outer peripheral surface 542a-1 formed by a tapered curved surface 542a-2 and a distal tapered surface 542a-3, and a seating portion 542b having a conical outer peripheral surface 542 b-1.

The needle 542 of the fifth embodiment can also suppress the occurrence of hunting in the same manner as the needle 242 of the second and third embodiments.

Fig. 12 is a schematic view showing a needle in a sixth embodiment.

The needle 642 shown in fig. 12 includes a distal end needle portion 642a having an outer peripheral surface 642a-1 formed by a conical surface 642a-2 and a tapered distal end curved surface 642a-3, and a seating portion 642b having a conical outer peripheral surface 642 b-1.

The needle 642 according to the sixth embodiment can also suppress the occurrence of oscillation in the same manner as the needle 242 according to the second and third embodiments.

The first to sixth embodiments described above are merely representative embodiments of the present invention, but the present invention is not limited thereto. That is, the present invention can be variously modified and implemented within a range not departing from the gist of the present invention. Even this modification is included in the scope of the present invention as long as the expansion valve and the refrigeration cycle of the present invention are provided.

For example, in the first to sixth embodiments, an expansion valve incorporated in the refrigeration cycle system 1 will be described as an example of the expansion valve. However, the application target of the expansion valve is not limited to the refrigeration cycle, and the application target is a target that can be set arbitrarily.

In the first to sixth embodiments, the expansion valve 13, which is attached to the valve main body so as to extend in the direction in which the cylindrical primary port 110 and the secondary port 130 are orthogonal to each other and which biases the needle valve and the diaphragm 153, is described as an example of the expansion valve. However, the specific configuration of the expansion valve such as the mounting direction of the primary port and the secondary port, and the urging structure of the needle valve and the diaphragm is not limited thereto, and may be set arbitrarily.

In the second embodiment corresponding to the leak port, one leak port 223 is provided at one position on the valve seat wall as an example of the leak port. However, if the leak port has a total port area corresponding to the leak flow rate, a plurality of positions may be provided.

In the third embodiment corresponding to the leakage groove, the leakage groove 321a in which a part of the inner peripheral surface 321a-2 of the through hole 321a of the valve port 321 is formed by a row of grooves recessed at one position is described as an example of the leakage groove. However, the leakage groove is not limited to this, and may be configured such that a part of the outer peripheral surface of the needle valve is recessed. Further, the number of grooves constituting the leak groove is not limited to one row, and for example, as shown in a modification of the third embodiment, the leak groove may be provided so as to have a plurality of rows of groove portions as long as the total groove area corresponding to the leak flow rate can be obtained.

In the first to sixth embodiments, the tapered needle 142, the needles 242a · 642a having various shapes of the tip needle portion 242a · 642a and the seat portion 242b · 642b are described as examples of the tip end side of the needle valve. However, the tip end side of the needle valve is not limited to these needles, and can be set arbitrarily.

In the second to sixth embodiments corresponding to the needle valve having the needle portion at the tip end and the seat portion, the seat portion 242b · 642b having the conical outer peripheral surface 242b-1 · 642b-1 is exemplified as an example of the seat portion. However, the seating portion is not limited to this, and may have a dome-shaped outer peripheral surface, for example, as long as it protrudes from the base of the distal end needle portion in a wide manner, and the specific shape thereof may be set arbitrarily.

In the first and third embodiments, an example of an expansion valve in which a gap corresponding to the leakage flow rate is opened between the

valve ports

121 and 321 and the needle valves 140 and 240 in order to allow the refrigerant of the leakage flow rate to flow therethrough in the valve-closed state is described. In the second embodiment, a mode in which the leak port 223 is provided instead of the above gap is described as an example. However, if the refrigerant of the leak flow rate flows in the closed valve state, there is no problem with the specific flow path of the refrigerant. However, the provision of the gap and the leakage port 223 can effectively ensure the leakage flow rate as described above.

In the second embodiment, an example of the expansion valve is described in which the annular gap area S21 between the inner peripheral surface of the valve port 221 and the root 242a-1 of the distal needle 242a is smaller than the port area Sb21 of the leakage port 223. In the third embodiment, the annular gap area S31 between the inner peripheral surface 321a-2 of the through hole 321a of the valve port 321 and the root 242a-1 of the distal needle 242a is smaller than the groove area Sb31 of the leakage groove 321 b. However, the relationship between the gap area and the size of the port area of the leak port and the groove area of the leak groove is not limited to this, and any relationship may be set. However, the above-described magnitude relationship can be adopted to more effectively suppress the generation of the oscillation.

Claims

1. An expansion valve, characterized in that,

the disclosed device is provided with:

a primary port into which a refrigerant for cooling an object to be cooled flows in a high-pressure state;

a valve body having a valve port through which the refrigerant flowing into the primary port is expanded to a low-pressure state;

a secondary port for allowing the refrigerant to pass through the valve port;

a needle valve which is tapered in an axial direction of the valve port, is provided in the valve main body so as to be movable in the axial direction with a tip end side thereof facing the valve port, and increases or decreases a flow rate of the refrigerant passing through the valve port by changing an opening degree of the valve port by approaching or separating the needle valve from the valve port in the axial direction;

a drive element having an operation chamber capable of changing an internal pressure and a diaphragm that moves in the axial direction in accordance with a change in the internal pressure of the operation chamber to cause the needle valve to approach or separate from the valve port; and

a temperature sensing unit for changing the internal pressure of the operation chamber in the driving element according to the temperature change of the object to be cooled,

the refrigerant passes through the secondary port at a predetermined leakage flow rate even in a closed state where the needle valve is closest to the valve port,

the outer peripheral surface of the needle valve on the tip side has a shape in which an inclination angle on an acute angle side with respect to a connecting plane of the outer peripheral surface with respect to a central axis of the needle valve increases toward the tip of the needle valve.

2. An expansion valve according to claim 1,

in the valve-closed state, a gap corresponding to the leakage flow rate is opened between the valve port and the needle valve.

3. An expansion valve according to claim 2,

the valve port includes a through hole penetrating through a valve seat wall in the valve body to partition the primary port side and the secondary port side, a leak groove recessed so as to have a groove area corresponding to the leak flow rate in a plan view of the valve port and extending from the primary port side to the secondary port side, and a part of at least one of an inner peripheral surface of the through hole and an outer peripheral surface of the needle valve,

in the valve-closed state, the needle valve is in a seated state in which a peripheral surface thereof abuts against an edge of the through hole in the valve port,

in the seated state, the leak groove is opened as the clearance between the valve port and the needle valve.

4. An expansion valve according to claim 3,

the leakage groove has a plurality of groove portions each having a groove area whose total sum is an area corresponding to the leakage flow rate.

5. An expansion valve according to claim 1,

the valve port is provided with a through hole penetrating through a valve seat wall that separates the primary port side and the secondary port side in the valve body, and a leak port penetrating through the valve seat wall so as to obtain a port area corresponding to the leak flow rate in a plan view of the valve port,

the needle valve comprises: a tip needle portion having a tapered shape thinner than the valve port, at least a part of a root side of the tip needle portion being accommodated in the valve port in the valve-closed state; and a seating part which protrudes from a base part of the tip needle part in a wide end shape so as to be larger than an inner diameter of the valve port, and which is in a seating state in which a peripheral surface thereof abuts against an edge of the valve port in the valve-closed state,

in the above-described plan view, a gap area that is annularly opened between the inner peripheral surface of the valve port and the root portion of the distal end needle portion in the valve-closed state is smaller than the port area.

6. An expansion valve according to claim 1,

the valve port includes a through hole penetrating through a valve seat wall separating the primary port side and the secondary port side in the valve body, a leak groove recessed so as to obtain a groove area corresponding to the leak flow rate in a plan view of the valve port and extending from the primary port side to the secondary port side, and a part of at least one of an inner peripheral surface of the through hole and an outer peripheral surface of the needle valve,

the needle valve comprises: a tip needle portion having a tapered shape thinner than the through hole, at least a part of a root side of the tip needle portion being accommodated in the through hole in the valve-closed state; and a seating part which protrudes from a base of the tip needle part to have a wider end so as to be larger than an inner diameter of the through hole, and which is brought into a seating state in which a peripheral surface thereof abuts against an edge of the through hole in the valve-closed state,

in the planar view, an area of a gap opened in a ring shape between the inner peripheral surface of the through hole and the root portion of the distal end needle portion when the leak groove is not provided in the closed valve state is smaller than the groove area.

7. An expansion valve according to claim 6,

8. A refrigeration cycle system is characterized in that,

the disclosed device is provided with:

a compressor for compressing a refrigerant for cooling an object to be cooled;

a condenser for condensing the compressed refrigerant;

an expansion valve according to any one of claims 1 to 5 for expanding and depressurizing the condensed refrigerant; and

an evaporator for absorbing heat generated by the object to be cooled in the decompressed refrigerant and evaporating the refrigerant.