JP2007024351A - Refrigerant restricting device and connecting structure of check valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure of a check valve capable of preventing reverse connection of the check valve when the check valve is connected to a capillary tube in which a refrigerant is circulated. <P>SOLUTION: Connecting portions 16a, 16b, 16c, 16d, 16e, 16f of uniform diameter are formed at both end sides of the check valve 2B allowing the refrigerant to flow only in one direction. The indoor-side connecting portions 16d, 16e, 16f are provided with stoppers 20. The stoppers 20 control an insertion length at an indoor side to a length C. Beads 18 (projections) indicating inserting portions 19a of the length A are formed on an outdoor-side end portion of the capillary tube 3 for heating and end portions of outdoor-side capillary tubes 9, 10. The length A of the inserting portion 19a is determined to be longer than the length C controlled by the stopper 20. The inserting portions 19a are inserted into the indoor-side inserting portions 16d, 16e, 16f. Thus the reverse connection of the check valve 2B can be found at first glance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a check valve and a heating capillary tube that bypass-connects both sides of the check valve, and is provided in a refrigeration cycle of a heat pump type air conditioner with different pressure reduction amounts during cooling and heating. The present invention relates to a refrigerant throttling device for depressurizing a refrigerant, and a check valve connection structure for connecting a flow pipe and a check valve.

  In general, in a refrigeration cycle of a heat pump air conditioner that also functions as an air conditioner by switching the refrigerant circulation direction, the refrigerant flowing between the outdoor heat exchanger and the indoor heat exchanger is decompressed (squeezed). A refrigerant throttle device is provided.

  FIG. 11 shows an example of a refrigerant throttle device of a heat pump type air conditioner. The refrigerant throttle device 1C depressurizes the refrigerant by different pressure reduction amounts (throttle amounts) during cooling and heating, and includes a check valve 2C for circulating the refrigerant from the outdoor side to the indoor side, and a check valve 2C. A heating capillary tube 3 that bypasses both sides and distributes the refrigerant from the indoor side to the outdoor side, and a cooling and heating capillary tube 4 that is connected to the indoor side of the check valve 2C and distributes the refrigerant in both directions are provided. .

  During the cooling, the refrigerant traveling from the outdoor side to the indoor side passes through the check valve 2C and is reduced in pressure when flowing through the cooling / heating capillary tube 4, and is connected to the indoor side of the cooling / heating capillary tube 4 via the branch pipe 5. The air is rectified by the two indoor capillary tubes 6 and 7 and is sent to the two refrigerant inlets of the indoor heat exchanger.

  The refrigerant flowing from the indoor side to the outdoor side during heating is decompressed when flowing through the capillary tube 4 for heating / cooling restriction and the capillary tube 3 for heating, and is connected to the outdoor side of the check valve 2C via the branch pipe 8. The air is rectified by the outdoor outdoor capillary tubes 9 and 10 and fed into the two refrigerant inlets of the outdoor heat exchanger.

For example, Patent Documents 1 and 2 disclose a refrigerant throttle device including a check valve and a capillary tube.
JP-A-6-201228 JP 2001-174106 A

  By the way, the refrigerant throttling device 1C includes a check valve 2C, a heating capillary tube 3, a cooling / heating capillary tube 4, a branch pipe 5, indoor capillary tubes 6, 7, branch pipe 8, and outdoor capillary tubes 9, 10. The number of parts is large, and accordingly, the number of man-hours for assembling the refrigerant throttle device is also increased.

  Further, the check valve 2C is a component whose flow direction is determined, and when assembling the refrigerant throttle device, it is necessary to arrange the flow direction from the outdoor side toward the indoor side by using the display 11. As shown in FIG. 12, when the inner diameters (D1, D2) of the connecting portions 2Ca, 2Cb on both sides are different sizes (D1> D2), the reverse connection of the check valve 2C is prevented. When the inner diameters (D1, D2) of the connecting portions 2Ca, 2Cb are the same (D1 = D2), the check valve 2C may be reversely connected.

  The present invention provides a refrigerant throttle device that can be easily assembled by reducing the number of parts, and further provides a check valve connection structure that can prevent reverse connection of the check valve. Objective.

  In view of the above problems, the refrigerant throttle device according to the present invention is provided between an outdoor heat exchanger and an indoor heat exchanger in a refrigeration cycle in which the refrigerant flow direction is opposite between the cooling operation and the heating operation. And a check valve that circulates only the refrigerant from the outdoor heat exchanger side to the indoor heat exchanger during cooling operation and prevents the refrigerant from flowing in the reverse direction, and is connected in parallel to the check valve for heating. A capillary tube for heating that circulates refrigerant from the indoor heat exchanger to the outdoor heat exchanger during operation, a plurality of outdoor capillary tubes arranged in parallel outside the check valve, and a check valve And a plurality of indoor capillary tubes arranged in parallel on the indoor side.

  A plurality of connecting portions for connecting the capillary tubes are formed at both ends of the check valve, and the plurality of outdoor capillary tubes and the plurality of indoor capillary tubes are directly connected to the both end connecting portions of the check valve. Then, the branching tube for connecting the outdoor capillary tube and the indoor capillary tube to the check valve is omitted, and further, a cooling / heating capillary dedicated to decompression is used to reduce the pressure by circulating the refrigerant during cooling and heating. The tube can be omitted, and accordingly, the number of parts of the refrigerant throttle device can be reduced.

  When connecting a plurality of outdoor capillary tubes and a plurality of indoor capillary tubes to the check valve and omitting the branch pipe, the outdoor and indoor connection portions of the check valve have the same diameter. For this, reverse connection prevention means may be provided to prevent reverse connection of the check valve.

  The outdoor capillary tube and the indoor capillary tube can be connected to the check valve by inserting the insertion portion at one end thereof into the connection portion of the check valve. In this case, the insertion part of the outdoor capillary tube and the insertion part of the indoor capillary tube are set to different lengths. Furthermore, as a reverse connection preventing means, a length that can be inserted into the connection portion is inserted into a connection portion for inserting the shorter one of the insertion portions of the outdoor capillary tube and the indoor capillary tube among the connection portions of the check valve. A stopper is provided to limit the length to the same length as the shorter insertion portion.

  Then, in order to reversely connect the check valve, since the longer insertion portion is inserted into the connection portion provided with the stopper, the entire insertion portion cannot be inserted by the stopper. You can notice at a glance that the check valve is reversely connected.

  Further, the check valve connection structure according to the present invention is for connecting a flow pipe through which the fluid flows and a check valve that allows the fluid to flow only in one direction. When connecting the flow pipe to the check valve by providing a connection part of the same diameter for connecting the flow pipe and inserting the insertion part at one end of the flow pipe into the connection part of the check valve, both sides of the check valve At least one of the connecting portions is provided with a reverse connection preventing means for preventing reverse connection of the check valve.

  According to this configuration, for example, the connection portion of the check valve is colored in the same color as the insertion portion of the flow pipe, or the connection portion is provided with a protrusion or groove that meshes with the groove or protrusion formed in the insertion portion of the flow pipe. Thereby, even if the connection part provided in the both ends of the check valve is the same diameter, the reverse connection of the check valve in which the direction of fluid flow is determined can be prevented.

  One end side mark indicating the insertion portion is provided on the flow pipe connected to the connection portion on one end side of the check valve. Further, as a means for preventing reverse connection, the length of the connection portion on the other end side of the check valve that can be inserted into the connection portion on the other end side is restricted to a length different from the length of the insertion portion indicated by the one end side mark. A stopper is provided. Then, even if the insertion portion of the flow pipe to be connected to the connection portion on the one end side is inserted into the connection portion on the other end side, the insertion length regulated by the stopper and the insertion length indicated by the one end side mark are Since it is different, it can be noticed that the check valve is reversely connected.

  In addition, the insertion part to be inserted into the connection part on one end side may be shorter than the insertion part to be inserted into the connection part on the other end side, but the insertion to be inserted into the connection part on one end side relative to the connection part on the other end side. It is more preferable to set the part longer. As a result, when the insertion part of the flow pipe to be connected to the connection part on the one end side is inserted into the connection part on the other end side, the one end side mark is hidden in the connection part or inserted by the one end side mark before the stopper functions It is possible to prevent the insertion of the part from being blocked.

  The other end side mark which shows the insertion part of the length equal to the length regulated by the stopper is provided in the flow pipe connected to the connection part on the other end side of the check valve. Then, by inserting the insertion portion of the flow pipe to be connected into the connection portion on the other end side, the insertion length restricted by the stopper on the other end side and the insertion length indicated by the other end side mark Since they match, it can be confirmed that the check valve is correctly connected.

  A projection as one end side mark is formed on the flow pipe connected to the connection portion on one end side of the check valve, and the insertion portion indicated by the projection is set longer than the length regulated by the stopper. If it does so, the insertion length to the connection part of the one end side can be controlled to predetermined | prescribed length using the protrusion as a one end side mark. Since the insertion portion indicated by the protrusion is longer than the insertion portion on the other end side, when the insertion portion of the flow pipe to be connected to the connection portion on the one end side is inserted into the connection portion on the other end side, the protrusion protrudes from the connection portion. It can be noticed at first glance that it has lifted and the check valve is reversely connected.

  If the flow pipe connected to the connection portion on the other end side of the check valve is formed with a protrusion as a mark on the other end side, when the insertion of the flow pipe to be connected is inserted into the connection portion on the other end side, the stopper In addition to this, it is possible to restrict the insertion length to a predetermined length using a protrusion as a mark on the other end side. As a result, the insertion length can be set more accurately and reliably.

  The protrusion as the one end side mark or the other end side mark may protrude from a part of the peripheral surface of the flow pipe, but its strength can be increased if it is continuous in the circumferential direction. It is preferable. As this protrusion, a bead formed by beading can be exemplified.

  One connecting portion may be provided at each end portion of the check valve, but it is formed by branching from the both end portions of the check valve so that a plurality of flow pipes can be connected. Also good. When connecting a plurality of flow pipes directly to a check valve without using a branch pipe or the like, the connection part on one end side and the connection part on the other end side tend to have the same diameter, and the present invention is preferably employed. can do.

According to the present invention, the rectifying outdoor capillary tube and the indoor capillary tube have a pressure reducing function, and further, by directly connecting them to the check valve, a dedicated capillary tube for decompressing the refrigerant is provided. Since the branch pipe is omitted, the number of parts of the refrigerant throttle device can be reduced and the assembly thereof can be facilitated.For example, when assembling the refrigerant throttle device of a heat pump air conditioner, the check valve is reversed. Even if it is arranged in the direction, it can be noticed at a glance. Thereby, it can reconnect correctly, without brazing in the reverse direction, and the reverse connection of the check valve to the flow pipe can be prevented.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the refrigerant throttle device and check valve connection structure according to the present invention will be described below with reference to the drawings.

[First Embodiment]
First, a first embodiment of the refrigerant throttle device according to the present invention will be described. FIG. 1 is a refrigeration cycle diagram including the refrigerant throttle device according to the present invention, and FIG. 2 is a plan view of the refrigerant throttle device of the first embodiment. FIG. 3 is a view showing a check valve, in which (a) is a rear view, (b) is a plan view, and (c) is a front view. FIG. 4 is a cross-sectional view of the check valve.

  The refrigeration cycle shown in FIG. 1 is installed in, for example, a heat pump type integrated air conditioner, and includes a compressor 12 that compresses refrigerant gas, a four-way switching valve 13 that switches a refrigerant circulation direction, and an outdoor side. A refrigerant provided between the two-pass outdoor heat exchanger 14 for heat exchange, the two-pass indoor heat exchanger 15 for heat exchange indoors, and the outdoor heat exchanger 14 and the indoor heat exchanger 15 And a refrigerant throttle device 1A that depressurizes (squeezes) the refrigerant, and is piped so that the refrigerant passes through them.

  This refrigeration cycle is used for both cooling and heating by operating the four-way switching valve 13 to circulate the refrigerant in the direction indicated by the solid line arrow during cooling and to circulate the refrigerant in the direction indicated by the broken line arrow during heating.

  The refrigerant throttling device 1A is for depressurizing the refrigerant by a different depressurization amount during cooling and during heating. Only the refrigerant flowing from the outdoor side to the indoor side is circulated during cooling so that the refrigerant flows in the reverse direction. A check valve 2A for blocking, a heating capillary tube 3 that is connected in parallel to the check valve 2A and distributes the refrigerant from the indoor side to the outdoor side during heating and decompresses, and in parallel to the outdoor side of the check valve 2A The two outdoor capillary tubes 9 and 10 that rectify and depressurize the refrigerant and the two indoor capillary tubes 6 that are arranged in parallel to the indoor side of the check valve 2A and rectify and depressurize the refrigerant. , 7.

  The check valve 2 </ b> A includes a hollow check valve body 16 with a display 11 indicating the flow direction, and a valve body 17 that blocks the flow of the refrigerant from the indoor side to the outdoor side. In the check valve 2A, when the refrigerant moves from the outdoor side (lower side in FIG. 4) to the indoor side (upper side in FIG. 4), the valve body 17 is opened by the fluid pressure of the refrigerant, and the refrigerant moves from the indoor side to the outdoor side. When heading, the valve body 17 is closed by the fluid pressure of the refrigerant.

  The check valve main body 16 has three connecting portions 16a, 16b, 16c branched at the end portion on the outdoor side of the cylindrical body, and three connecting portions 16d branched at the end portion on the indoor side of the cylindrical body, 16e and 16f are formed. The connection parts 16a, 16b, 16c and the connection parts 16d, 16e, 16f are formed by crushing two places at both ends of the cylindrical body.

  Beads 18 are formed by beading in the vicinity of both ends of the heating capillary tube 3 and in the vicinity of one end of the outdoor capillary tubes 9, 10 and the indoor capillary tubes 6, 7. 19 When the insertion portion 19 is inserted into the connection portions 16a, 16b, 16c and the connection portions 16d, 16e, 16f, the bead 18 functions as a stopper for regulating the insertion length to a predetermined insertion length.

  The heating capillary tube 3 is bypass-connected on both sides of the valve body 17 by inserting the insertion portions 19 at both ends into the connection portions 16a and 16d on both sides of the check valve 2A and directly connecting them.

  The outdoor-side capillary tubes 9 and 10 are connected directly to the outdoor-side connection portions 16b and 16c of the check valve 2A without using a branch pipe or the like. Thus, the refrigerant is stably distributed to the two refrigerant inlets of the outdoor heat exchanger 14.

  The indoor side capillary tubes 6 and 7 are connected directly to the indoor side connecting parts 16e and 16f of the check valve 2A without using a branch pipe or the like, and the other end is connected by the rectifying function. The refrigerant is stably distributed to the two refrigerant inlets of the indoor heat exchanger 15.

  Next, a procedure for connecting the heating capillary tube 3, the outdoor capillary tubes 9, 10 and the indoor capillary tubes 6, 7 to the check valve 2A will be described. First, the check valve 2A is arranged in a predetermined direction on the basis of the indication 11 such as stamping, printing, or sticking a sticker attached to the check valve 2A.

  Next, until the bead 18 hits the connection portions 16a, 16b, 16c and the connection portions 16d, 16e, 16f, the insertion portions 19 at both ends of the heating capillary tube 3 are inserted into the connection portions 16a, 16d on both sides of the check valve 2A. The insertion part 19 at one end of the outdoor capillary tubes 9 and 10 is inserted into the connection parts 16b and 16c on the outdoor side of the check valve 2A, and the insertion part 19 at one end of the indoor capillary tubes 6 and 7 is inserted into the check valve 2A. Are inserted into the connecting portions 16e and 16f on the indoor side.

  Thereafter, the heating capillary tube 3, the outdoor capillary tubes 9, 10 and the indoor capillary tubes 6, 7 are brazed to the connecting portions 16a, 16b, 16c and the connecting portions 16d, 16e, 16f on both sides. Thereby, the heating capillary tube 3, the outdoor capillary tubes 9, 10 and the indoor capillary tubes 6, 7 are reliably connected to the check valve 2A.

  Next, how the refrigerant flows through the refrigerant expansion device 1A will be described. During cooling, the high-temperature and high-pressure refrigerant in the compressor 12 is guided to the outdoor heat exchanger 14 by the four-way switching valve 13, and after radiating and condensing in the outdoor heat exchanger 14, the outdoor capillary tube 9 10, the pressure is reduced and enters the check valve 2A. After passing through the check valve 2A as it is, the pressure is reduced by flowing through the indoor capillary tubes 6 and 7, and the heat is absorbed and evaporated in the indoor heat exchanger 15, and then passes through the four-way switching valve 13 to the compressor 12. Return.

  At the time of heating, the high-temperature and high-pressure refrigerant in the compressor 12 is led to the indoor heat exchanger 15 by the four-way switching valve 13, and after radiating and condensing in the indoor heat exchanger 15, the indoor capillary tube 6 , 7 and the pressure is reduced, and the inside of the check valve 2A is more indoor than the valve body 17 of the check valve 2A. Without passing through the check valve 2A, the pressure is reduced by flowing through the heating capillary tube 3, enters the outdoor side of the valve body 17 of the check valve 2A, and flows through the outdoor capillary tubes 9 and 10 to reduce the pressure. Then, after absorbing and evaporating in the outdoor heat exchanger 14, it passes through the four-way switching valve 13 and returns to the compressor 12.

  The outdoor capillary tubes 9 and 10 and the indoor capillary tubes 6 and 7 have a sufficient throttling function (decompression function) that does not require a dedicated decompression capillary tube. The two refrigerant inlets of the exchanger are stably distributed. The outdoor capillary tubes 9 and 10 and the indoor capillary tubes 6 and 7 are directly connected to the connection portions 16b and 16c and the connection portions 16e and 16f of the check valve 2A, so that they branch to the check valve 2A. No tube is required.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 5 is a plan view of the refrigerant throttle device of the second embodiment, and FIG. 6 is a side view of the heating capillary tube. FIG. 7 is a view showing a check valve, in which (a) is a rear view, (b) is a plan view, and (c) is a front view. FIG. 8 is a cross-sectional view of the check valve.

  The refrigerant throttle device 1B of the second embodiment has substantially the same configuration as the refrigerant throttle device 1A of the first embodiment, but the connection portions 16a, 16b, 16c and the connection portions 16d, 16e on both sides of the check valve 2B, This is employed when the inner diameter (D) of 16f is set to the same diameter, and prevents reverse connection of the check valve 1A as shown in FIG. That is, reverse connection preventing means for preventing reverse connection of the check valve 2B when connecting the heating capillary tube 3, the outdoor capillary tubes 9, 10 and the indoor capillary tubes 6, 7 to the check valve 2B. Is provided.

  An insertion portion 19 a is formed at the outdoor end of the heating capillary tube 3 and at one end of the outdoor capillary tubes 9, 10, and the indoor end of the heating capillary tube 3 and the indoor capillary tubes 6, 7 An insertion portion 19b is formed at one end. And the length (A) of the insertion part 19a is set longer than the length (B) of the insertion part 19b (A> B).

  A protruding stopper 20 as a reverse connection prevention means is provided inside the hole of the connection portion 16d, 16e, 16f on the indoor side of the check valve 2B. The stopper 20 abuts the tips of the insertion portions 19b of the heating capillary tube 3 and the indoor capillary tubes 6 and 7, and regulates the length that can be inserted into the connection portions 16d, 16e, and 16f to (C). It is like that. The length (C) is set shorter than the length (A) of the insertion portion 19a (A> C) and equal to the length (B) of the insertion portion 19b (B = C).

  As shown in FIG. 10, even if the check valve 1B is disposed in the reverse direction and the insertion portion 19a is to be inserted into the connection portions 16d, 16e, and 16f, the insertion portion 19a Only a length (C) shorter than the length (A) can be inserted. Accordingly, the insertion portion 19a cannot be pushed into the connection portions 16d, 16e, and 16f until the bead 18 is brought into contact with the peripheral edges of the holes of the connection portions 16d, 16e, and 16f, and the check valve 1 is disposed in the reverse direction. You can notice at a glance. Other configurations are the same as those of the first embodiment.

  In addition, this invention is not limited to said embodiment, A change can be suitably added within the scope of the present invention. For example, the refrigerant throttle device is equipped not only for the refrigeration cycle of an integrated heat pump type air conditioner but also for the refrigeration cycle of a heat pump type air conditioner including an indoor unit and an outdoor unit. Also good.

  The check valves 2A and 2B are connected to the heating capillary tube 3, the outdoor capillary tubes 9 and 10 and the indoor capillary tubes 6 and 7 by connecting the connecting portions 16a, 16b and 16c of the check valves 2A and 2B. Instead of inserting the insertion part 19 of each capillary tube into the parts 16d, 16e, and 16f, the connection part of the check valves 2A and 2B may be inserted into the insertion part 19 of each capillary tube.

  The check valve 2B provided with the reverse connection preventing means is not limited to the one provided in the refrigeration cycle, and may be connected to a flow pipe through which other fluid flows. In this case, the check valve 2B only needs to have the same diameter at both ends, and instead of directly connecting a plurality of flow pipes to the check valve 2B, the check valve 2B is connected via a branch pipe of the same diameter. You may do. Further, the connection portions 16a, 16b, 16c and the connection portions 16d, 16e, 16f on both ends of the check valve 2B do not have to have the same diameter, and a pair of connection portions (16a, 16d, 16b and 16e, 16c, and 16f) may have the same diameter.

  The stopper 20 can be provided not only on the indoor side of the check valve 2B (the tip side of the arrow indicating the flow direction) but also on the outdoor side. In this case, the insertion part 19a on the outdoor side is set shorter than the insertion part 19b on the indoor side. Further, stoppers 20 can be provided on both sides of the check valve 2B. In this case, the insertion lengths regulated by the stoppers 20 are set to different lengths. The shape of the stopper 20 is not limited to a protruding shape, and may be a taper that restricts the insertion of the flow pipe.

  Further, instead of forming a bead surrounding the entire circumference of the capillary tube by beading, a protrusion protruding from a part in the circumferential direction may be provided. Furthermore, a configuration in which a mark such as coloring is provided instead of the protrusion (bead) can be employed. In this case, stoppers 20 may be provided on both end sides of the check valve 2B.

Refrigeration cycle diagram including the refrigerant throttle device according to the present invention The top view of the refrigerant throttle device of a 1st embodiment It is a figure which shows a non-return valve, (a) is a rear view, (b) is a top view, (c) is a front view. Cross section of check valve The top view of the refrigerant throttle device of 2nd Embodiment Side view of capillary tube for heating It is a figure which shows a non-return valve, (a) is a rear view, (b) is a top view, (c) is a front view. Cross section of check valve Top view of refrigerant throttle device with reverse connection of check valve Plan view of refrigerant throttle device with reverse connection of check valve having stopper Plan view of a conventional refrigerant throttle device It is a figure which shows the conventional check valve, (a) is a rear view, (b) is a top view, (c) is a front view.

Explanation of symbols

1A, 1B Refrigerant throttle device 2A, 2B Check valve 3 Heating capillary tube 6, 7 Indoor side capillary tube 9, 10 Outdoor side capillary tube 18 Bead 19 Insertion part 20 Stopper

Claims (10)

In the refrigeration cycle where the refrigerant flow direction is opposite between the cooling operation and the heating operation,
Provided between the outdoor heat exchanger and the indoor heat exchanger, during the cooling operation, only the refrigerant from the outdoor heat exchanger side to the indoor heat exchanger is circulated to prevent the refrigerant from flowing in the reverse direction. A check valve, a heating capillary tube connected in parallel to the check valve and flowing refrigerant from the indoor heat exchanger to the outdoor heat exchanger during heating operation, and in parallel to the outdoor side of the check valve A plurality of outdoor capillary tubes arranged on the inside, and a plurality of indoor capillary tubes arranged in parallel on the indoor side of the check valve,
A plurality of connection portions for connecting capillary tubes are formed at both ends of the check valve, and a plurality of outdoor capillary tubes and a plurality of indoor capillary tubes are directly connected to both end connection portions of the check valve. A refrigerant throttling device for a refrigeration cycle, characterized by being connected.   2. The check valve according to claim 1, wherein connecting portions on the outdoor side and the indoor side of the check valve are set to have the same diameter, and reverse connection preventing means for preventing reverse connection of the check valve is provided. The refrigerant throttle device according to claim 1. The outdoor capillary tube and the indoor capillary tube are connected to the check valve by inserting the insertion portion provided at one end thereof into the connection portion of the check valve,
The insertion part of the outdoor capillary tube and the insertion part of the indoor capillary tube are set to different lengths,
As the reverse connection preventing means, the shorter one of the insertion portions of the outdoor capillary tube and the indoor capillary tube is inserted into the connection portion of the check valve into which the shorter one is inserted. The refrigerant throttling device according to claim 2, wherein a stopper for regulating the length to be equal to the insertion portion is provided. A connection structure for connecting a flow pipe for circulating fluid and a check valve for circulating fluid only in one direction,
On both sides of the check valve, there are provided connection portions of the same diameter for connecting a flow pipe, and the flow pipe is reversed by inserting an insertion portion provided at one end thereof into the connection portion of the check valve. A check valve, wherein the check valve is connected to a check valve, and at least one of the connecting portions on both sides of the check valve is provided with a reverse connection prevention means for preventing the check valve from being reverse connected. Connection structure. One end side mark indicating the insertion portion is provided in the flow pipe connected to the connection portion on one end side of the check valve,
As the reverse connection preventing means, the length that can be inserted into the connection portion on the other end side of the check valve is restricted to a length different from the length of the insertion portion indicated by the one end side mark. The check valve connection structure according to claim 4, wherein a stopper is provided.   The other end side mark indicating the insertion portion having a length equal to the length regulated by the stopper is provided in the flow pipe connected to the connection portion on the other end side of the check valve. The check valve connection structure according to claim 5.   The flow pipe connected to the connection portion on one end side of the check valve is formed with a protrusion as the one end side mark, and the insertion portion indicated by the protrusion is set longer than the length regulated by the stopper. The check valve connection structure according to claim 5 or 6.   The check valve connection structure according to claim 6, wherein a protrusion as the mark on the other end side is formed on a flow pipe connected to a connection portion on the other end side of the check valve.   9. The check valve connection structure according to claim 7, wherein the protrusion as the one end side mark or the other end side mark is a bead formed by beading.   10. The check according to any one of claims 4 to 9, wherein the connecting portion is formed by branching into a plurality from both ends of the check valve so that a plurality of flow pipes can be connected. Valve connection structure.

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