Refrigerant piping, refrigeration equipment, and brazing method for refrigerant piping

Abstract

For stainless steel refrigerant piping, ensure sufficient pressure resistance to handle high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide. [Solution] The refrigerant piping 110 constitutes the refrigerant circuit 103 of the refrigeration device 100, and is a refrigerant piping through which a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide flows. The refrigerant piping 110 includes a first pipe 111 made of stainless steel and having a first end 113, a second pipe 112 made of stainless steel and having a second end 114, a first connecting part 10 made of a material other than stainless steel having a tensile strength lower than that of stainless steel and joined to the first end 113, and a second connecting part 20 made of the same material other than stainless steel and joined to the second end 114. The refrigerant piping 110 of this embodiment includes a connecting part 120 that connects the first pipe 111 and the second pipe 112, and a reinforcing member 30 arranged on the outer circumferential surface 123 of the connecting part 120.

Description

Technical Field

[0001] The present disclosure relates to a refrigerant pipe, a refrigeration apparatus, and a brazing method for a refrigerant pipe.

Background Art

[0002] Conventionally, stainless steel refrigerant pipes in which stainless steel pipes are connected to each other are known (see Patent Document 1). Stainless steel refrigerant pipes are generally connected by furnace brazing using a furnace installed in a factory or the like, and it is difficult to perform manual brazing at an installation site of a refrigeration apparatus or the like. In the refrigerant pipe of Patent Document 1, a copper joint is provided at a connection portion between stainless steel pipes, and the copper joints are brazed to each other, thereby enabling manual brazing between stainless steel pipes.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0004] However, in a refrigerant pipe in which stainless steel pipes are connected to each other via copper joints, the connection portion formed by the copper joints has lower pressure resistance than the stainless steel pipe portions. For this reason, it is difficult for conventional stainless steel refrigerant pipes to secure pressure resistance that can be used for high-pressure refrigerants such as a single refrigerant composed of carbon dioxide or a mixed refrigerant containing carbon dioxide.

[0005] An object of the present disclosure is to secure pressure resistance that allows a stainless steel refrigerant pipe to be used with high-pressure refrigerants such as a single refrigerant composed of carbon dioxide or a mixed refrigerant containing carbon dioxide.

Means for Solving the Problem

[0006] (1) The refrigerant piping of the present disclosure constitutes a refrigerant circuit of a refrigeration system and is a refrigerant piping through which a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide flows, and includes a first pipe made of stainless steel and having a first end, a second pipe made of stainless steel and having a second end, a first connecting part made of a material other than stainless steel having a tensile strength lower than that of stainless steel and joined to the first end, and a second connecting part made of copper and joined to the second end, and comprises a connecting part connecting the first pipe and the second pipe, and a reinforcing member arranged on the outer surface of the connecting part.

[0007] The refrigerant piping of this disclosure can have its pressure resistance at the connection point improved by the use of reinforcing members. As a result, the refrigerant piping of this disclosure, in the case of stainless steel refrigerant piping, can ensure pressure resistance that can be used with high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide.

[0008] (2) In the refrigerant piping of (1) of the present disclosure, the connection portion includes a first portion that radially overlaps with the first or second piping, and a second portion that extends axially from the first portion and does not radially overlap with the first and second piping, wherein the reinforcing member is preferably disposed on the outer circumferential surface of the second portion.

[0009] The refrigerant piping with the above configuration can improve the pressure resistance of the second portion, which does not overlap radially with the first or second piping and therefore has lower pressure resistance.

[0010] (3) In the refrigerant piping of the present disclosure as described in (2) above, the first connection portion and the second connection portion are made of copper, and it is preferable that the axial length of the second portion is greater than the axial length of the first portion.

[0011] The second part, which is made of copper, has the function of fixing the brazing material that has penetrated into the pipe. In the refrigerant piping of this disclosure, the brazing material that has penetrated into the refrigerant piping can be fixed to the second part by making the axial length of the second part greater than the axial length of the first part.

[0012] (4) In the refrigerant piping according to the embodiment of (2) of the present disclosure, the first connection portion and the second connection portion are preferably made of copper, and the radial thickness of the second portion is less than or equal to the radial thickness of the first pipe and the second pipe.

[0013] In the refrigerant piping configuration described above, the connection section having the second part can be constructed using a thin copper pipe. In this case, the pressure resistance of the connection section can be ensured while using a thin, inexpensive copper pipe. This makes it possible to reduce the cost of refrigerant piping with improved pressure resistance.

[0014] (5) In the refrigerant piping according to the embodiment of (3) of the present disclosure, it is preferable that in the first piping, the first end is open toward one side in the axial direction, in the second piping, the second end is open toward the other side in the axial direction, the first connection portion has the second portion extending from the first portion toward one side in the axial direction, and the inner circumferential surface of the first connection portion toward one side in the axial direction and the outer circumferential surface of the second connection portion toward the other side in the axial direction are joined by the brazing material.

[0015] In the refrigerant piping configuration described above, the brazing material that has penetrated into the refrigerant piping from between the inner surface on one axial side of the first connection and the outer surface on the other axial side of the second connection can be fixed to the second portion. This prevents the brazing material that has penetrated into the refrigerant piping from reaching the stainless steel first and second pipes.

[0016] (6) In any embodiment of the refrigerant piping of the present disclosure (1) to (5) above, the first connection portion preferably has a flared portion formed at one end on the axial side, and the second connection portion is connected to the flared portion.

[0017] In the refrigerant piping configuration described above, the second connection can be positioned by the flared portion when connecting the second connection to the first connection.

[0018] (7) In any embodiment of the refrigerant piping described in (1) to (6) above, the reinforcing member is preferably made of metal and brazed to the first connection portion.

[0019] The refrigerant piping of this disclosure can have its pressure resistance at the connection point improved by the use of reinforcing members. As a result, the refrigerant piping of this disclosure, in the case of stainless steel refrigerant piping, can ensure pressure resistance that can be used with high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide.

[0020] (8) In the refrigerant piping according to the embodiment of (7) of the present disclosure, the reinforcing member is preferably made of stainless steel.

[0021] The refrigerant piping of this disclosure can ensure the pressure resistance strength of the reinforcing members, thereby improving the pressure resistance strength of the connection parts.

[0022] (9) The refrigeration apparatus of the present disclosure comprises the refrigerant piping in any of the embodiments of (1) to (8) above.

[0023] The refrigeration apparatus of this disclosure can use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide, by using refrigerant piping in which the pressure resistance strength of the connection part is improved by reinforcing members.

[0024] (10) A brazing method for a refrigerant pipe according to the present disclosure relates to a refrigerant pipe comprising: a first pipe made of stainless steel and having a first end portion; a second pipe made of stainless steel and having a second end portion; a first connection portion made of a material other than stainless steel whose tensile strength is lower than that of stainless steel and joined to the first end portion; a second connection portion made of said material other than stainless steel and joined to the second end portion, the connection portion connecting the first end portion and the second end portion; and a reinforcing member disposed on an outer circumferential surface of the connection portion, wherein the connection portion includes a first portion radially overlapping the first pipe, and a second portion extending upward from the first portion and not radially overlapping the first pipe or the second pipe, an axial length of the second portion is made larger than an axial length of the first portion, and in a state where the first pipe is arranged in a posture such that the first end portion faces upward, and the second pipe is arranged in a posture such that the second end portion faces downward, an inner circumferential surface of an upper end portion of the first connection portion and an outer circumferential surface of a lower end portion of the second connection portion are brazed.

[0025] The brazing method for a refrigerant pipe according to the present disclosure enables manual brazing of a stainless steel refrigerant pipe with ensured pressure resistance that can use a high-pressure refrigerant such as a single refrigerant composed of carbon dioxide or a mixed refrigerant containing carbon dioxide. The brazing method for a refrigerant pipe according to the present disclosure can suppress, by means of the second portion, the brazing material that has penetrated into the refrigerant pipe from reaching the first pipe and the second pipe made of stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [Figure 1] FIG. 1 is a schematic diagram showing a refrigeration apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic cross-sectional view schematically showing a connection portion of a refrigerant pipe according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic cross-sectional view schematically showing a first pipe and a first connection portion of a refrigerant pipe according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view schematically showing a second pipe and a second connection portion of a refrigerant pipe according to an embodiment of the present disclosure. [Figure 5] Figure 5 is a schematic cross-sectional view illustrating the condition of the refrigerant piping connection (during brazing) according to the embodiment of this disclosure. [Modes for carrying out the invention]

[0027] The refrigerant piping and refrigeration systems having said refrigerant piping described herein will be described in detail below with reference to the attached drawings. However, this disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope of the claims as indicated by the claims.

[0028] [Overall configuration of the refrigeration system] Figure 1 is a schematic diagram showing a refrigeration system according to an embodiment of the present disclosure. The refrigeration system 100 shown in this embodiment is an air conditioning system that adjusts the temperature and humidity of an air-conditioned room by a vapor compression type refrigeration cycle. The refrigeration system 100 includes an outdoor unit 101 installed outside and an indoor unit 102 installed inside. The outdoor unit 101 and the indoor unit 102 are connected to each other by refrigerant piping 110. Although this embodiment illustrates a refrigeration system 100 with one indoor unit 102, the refrigeration system 100 of the present disclosure may be configured to include two or more indoor units 102. Although the refrigeration system 100 shown in this embodiment is an air conditioning system, the refrigeration system of the present disclosure is not limited to an air conditioning system and may be a refrigerator, freezer, water heater, etc.

[0029] The refrigeration system 100 includes a refrigerant circuit 103 that performs a vapor compression type refrigeration cycle. The refrigerant circuit 103 includes a plurality of component parts and refrigerant piping 110 that connects the plurality of component parts. The refrigerant piping 110 includes a connection part 120. The configuration of the connection part 120 will be described in detail later.

[0030] The refrigerant circuit 103 includes multiple components such as a compressor 104 that compresses the refrigerant to produce high-temperature, high-pressure gaseous refrigerant, multiple indoor heat exchangers 105, an expansion valve 106 that reduces the pressure of the refrigerant, an outdoor heat exchanger 107, an accumulator 108, and a four-way switching valve 109, all of which are connected by refrigerant piping 110.

[0031] The refrigeration system 100 of this disclosure uses a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide (a so-called natural refrigerant) as the refrigerant. The refrigerant flowing through the refrigerant circuit 103 is at a pressure of 4.0 MPa or higher (for example, about 8 to 14 MPa). Therefore, the refrigerant piping 110 used in the refrigeration system 100 has strength to withstand a pressure of 4.0 MPa or higher. The refrigerant piping 110 used in the refrigeration system 100 is mostly made of stainless steel, and includes some parts made of materials other than stainless steel (for example, copper). Therefore, the refrigerant piping 110 of this disclosure has higher pressure resistance strength compared to refrigerant piping used in refrigerant circuits using refrigerants such as R32 and R410A. The stainless steel used in the refrigerant piping 110 of this embodiment is an austenitic stainless steel such as SUS304 or SUS304L, or a ferritic stainless steel such as SUS430, SUS436L, or SUS444. In this embodiment, the case is illustrated in which most (almost entirely) of the refrigerant piping 110 constituting the refrigerant circuit 103 is made of stainless steel. However, in the refrigeration system 100 of this disclosure, a portion of the refrigerant piping 110 constituting the refrigerant circuit 103 may be made of stainless steel.

[0032] The compressor 104 compresses low-pressure gaseous refrigerant and discharges high-pressure gaseous refrigerant. The compressor 104 has an inlet or suction section 104a and a discharge port or discharge section 104b. Low-pressure gaseous refrigerant is drawn in from the suction section 104a. High-pressure gaseous refrigerant is discharged from the discharge section 104b in the direction of arrow A. Various types of compressors, such as a scroll compressor, can be used as the compressor 104. The compressor 104 is housed in the casing 101a of the outdoor unit 101. The accumulator 108 is provided in the refrigerant piping 110 on the suction side of the compressor 104.

[0033] The indoor heat exchanger 105 is installed in the indoor unit 102 and performs heat exchange between the refrigerant and the indoor air. For example, the indoor heat exchanger 105 can be a cross-fin type fin-and-tube heat exchanger or a microchannel type heat exchanger. The indoor fan 131 is installed near the indoor heat exchanger 105. The indoor fan 131 blows indoor air to the indoor heat exchanger 105 and sends conditioned air into the room.

[0034] The expansion valve 106 is installed in the refrigerant piping 110 between the outdoor heat exchanger 107 and the indoor heat exchanger 105. The expansion valve 106 expands the refrigerant passing through it and reduces the pressure to a predetermined level. The expansion valve 106 in this embodiment is an electronic expansion valve.

[0035] The outdoor heat exchanger 107 performs heat exchange between the refrigerant and the outdoor air. The outdoor heat exchanger 107 can be, for example, a cross-fin type fin-and-tube heat exchanger or a microchannel type heat exchanger. The outdoor fan 132 is installed near the outdoor heat exchanger 107. The outdoor fan 132 blows outdoor air to the outdoor heat exchanger 107.

[0036] The refrigerant piping 110 is equipped with a four-way switching valve 109, a gas shut-off valve 133, and a liquid shut-off valve 134 for switching the refrigerant flow path. The refrigeration system 100 can switch between cooling and heating operation by reversing the flow of refrigerant by switching the four-way switching valve 109, and supplying the refrigerant discharged from the compressor 104 to the outdoor heat exchanger 107 and the indoor heat exchanger 105.

[0037] The gas shut-off valve 133 and the liquid shut-off valve 134 open or close the refrigerant path. Opening and closing are performed, for example, manually. The gas shut-off valve 133 and the liquid shut-off valve 134 are closed, for example, when the refrigeration system 100 is installed, to prevent the refrigerant sealed in the outdoor unit 101 from leaking to the outside. On the other hand, the gas shut-off valve 133 and the liquid shut-off valve 134 are open when the refrigeration system 100 is in use.

[0038] During heating operation of the refrigeration unit 100, the four-way switching valve 109 is switched as shown by the solid line, causing the refrigerant to flow in the direction indicated by the solid arrow. As a result, the high-pressure gaseous refrigerant discharged from the compressor 104 in the direction of arrow A passes through the four-way switching valve 109, then through the open gas shut-off valve 133, and enters the indoor heat exchanger 105. The high-pressure gaseous refrigerant dissipates heat in the indoor heat exchanger 105 as it becomes high-pressure liquid refrigerant. The high-pressure liquid refrigerant reaches the expansion valve 106 via the open liquid shut-off valve 134, where it is depressurized. The depressurized refrigerant reaches the outdoor heat exchanger 107, where it absorbs heat and becomes low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant is drawn into the compressor 104 via the four-way switching valve 109 and the accumulator 108. During heating operation, the indoor heat exchanger 105 functions as a heat radiator, and the outdoor heat exchanger 107 functions as a heat absorber.

[0039] On the other hand, during cooling operation, the flow of the refrigerant is reversed by switching the four-way switching valve 109 as shown by the dotted line, causing the refrigerant to flow in the direction indicated by the dotted arrow. As a result, the high-pressure gaseous refrigerant discharged from the compressor 104 in the direction of arrow A passes through the four-way switching valve 109 and enters the outdoor heat exchanger 107. The high-pressure gaseous refrigerant dissipates heat in the process of becoming high-pressure liquid refrigerant in the outdoor heat exchanger 107. The high-pressure liquid refrigerant reaches the expansion valve 106, where it is depressurized. The depressurized refrigerant passes through the open liquid shut-off valve 134 and reaches the indoor heat exchanger 105, where it absorbs heat and becomes low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant is drawn into the compressor 104 via the open gas shut-off valve 133, the four-way switching valve 109, and the accumulator 108. During cooling operation, the indoor heat exchanger 105 functions as a heat absorber, and the outdoor heat exchanger 107 functions as a heat radiator.

[0040] [Regarding refrigerant piping] As shown in Figure 1, in the refrigeration system 100 of this disclosure, the refrigerant piping 110 includes a first pipe 111 and a second pipe 112. The refrigerant piping 110 further includes a connecting portion 120 that connects the first pipe 111 and the second pipe 112. The first pipe 111, the second pipe 112, and the connecting portion 120 constitute a part of the refrigerant circuit 103.

[0041] The first piping 111 includes a refrigerant piping 110 located inside the outdoor unit 101 and a refrigerant piping 110 connecting the outdoor unit 101 to the connection part 120. The first piping 111 includes a first liquid refrigerant piping 111L and a first gaseous refrigerant piping 111G. Liquid refrigerant flows through the first liquid refrigerant piping 111L, and gaseous refrigerant flows through the first gaseous refrigerant piping 111G.

[0042] In the refrigeration system 100 of this disclosure, one of the two connection points 120 connects the first liquid refrigerant pipe 111L and the second liquid refrigerant pipe 112L, and the other of the two connection points 120 connects the first gas refrigerant pipe 111G and the second gas refrigerant pipe 112G. In the refrigerant piping 110 of this disclosure, the first pipe 111 and the second pipe 112 are made of stainless steel.

[0043] [Regarding refrigerant piping and connections] Figure 2 is a schematic cross-sectional view showing a connection portion of a refrigerant piping according to an embodiment of the present disclosure. Figure 3 is a schematic cross-sectional view showing the first pipe and first connection portion of the refrigerant piping according to an embodiment of the present disclosure. Figure 4 is a schematic cross-sectional view showing the second pipe and second connection portion of the refrigerant piping according to an embodiment of the present disclosure. Figure 2 shows the refrigerant piping 110 of the present disclosure. As shown in Figure 2, the connection portion 120 in the refrigerant piping 110 of the present disclosure is composed of a first connection portion 10, a second connection portion 20, and a reinforcing member 30. Of the parts constituting the connection portion 120, the first connection portion 10 and the second connection portion 20 are made of a material other than stainless steel. In this embodiment, the first connection portion 10 and the second connection portion 20 are made of copper. Of the parts constituting the connection portion 120, the reinforcing member 30 is made of metal. In the connection portion 120 of this embodiment, the reinforcing member 30 is made of stainless steel. The reinforcing member 30 may be made of a metal other than stainless steel, or it may be made of a material other than metal.

[0044] The following definitions apply to the refrigerant piping 110 of this disclosure. The direction along the central axis C of the refrigerant piping 110 is the "axial direction." Note that the "axial direction" includes the direction parallel to the central axis C. In the refrigerant piping 110, one side in the axial direction (the upper side in Figure 2) is the upper side, and the other side in the axial direction (the lower side in Figure 2) is the lower side. The direction perpendicular to the central axis C is the "radial direction," and the direction along a circle centered on the central axis C is the "circumferential direction."

[0045] As shown in Figures 2 and 3, the first connecting portion 10 is made of a cylindrical member and has an inner circumferential surface 11, an outer circumferential surface 12, an end portion 13, a straight pipe portion 14, and a flared portion 15. The first connecting portion 10 is made of copper. The end portion 13 includes a first end portion 13a on one axial side and a second end portion 13b on the other axial side. In this description, the first end portion 13a is also referred to as the upper end portion 13a, and the second end portion 13b is also referred to as the lower end portion 13b. The flared portion 15 is located at both axial ends of the straight pipe portion 14 and has a larger diameter than the straight pipe portion 14. The flared portion 15 includes a first flared portion 15a formed on the first end portion 13a and a second flared portion 15b formed on the second end portion 13b.

[0046] The first connection portion 10 is joined to the end portion 113 of the first pipe 111, for example, by furnace brazing. The end portion 113 of the first pipe 111 is also referred to as the first end portion 113. The connection portion 120 has a layer of brazing material 50 formed between the inner circumferential surface 11 of the first connection portion 10 and the outer circumferential surface 115 of the first end portion 113. The first connection portion 10 and the first pipe 111 are joined by a layer of brazing material 50 formed between the inner circumferential surface 11 and the outer circumferential surface 115 of the second flare portion 15b. In this description, the layer of brazing material 50 formed by furnace brazing is referred to as the first brazing material layer 51.

[0047] As shown in Figures 2 and 4, the second connecting portion 20 is made of a cylindrical member and has an inner circumferential surface 21, an outer circumferential surface 22, and an end portion 23. The second connecting portion 20 is made of copper. Copper is a material with a lower tensile strength than stainless steel. The end portion 23 includes a first end portion 23a on one axial side and a second end portion 23b on the other axial side. In this description, the first end portion 23a is also referred to as the upper end portion 23a, and the second end portion 23b is also referred to as the lower end portion 23b.

[0048] The second connection portion 20 is joined to the end portion 114 of the second pipe 112, for example, by furnace brazing. The end portion 114 of the second pipe 112 is also referred to as the second end portion 114. The connection portion 120 has a layer of brazing material 50 formed between the inner circumferential surface 21 of the second connection portion 20 and the outer circumferential surface 116 of the second end portion 114. The second connection portion 20 and the second pipe 112 are joined by the first brazing material layer 51 formed between the inner circumferential surface 21 and the outer circumferential surface 116.

[0049] As shown in Figures 2 and 3, the reinforcing member 30 is made of a cylindrical member and has an inner circumferential surface 31 and an outer circumferential surface 32. The reinforcing member 30 in this embodiment is made of stainless steel. The reinforcing member 30 is joined to the outer circumferential surface 12 of the straight pipe portion 14 of the first connection portion 10 by, for example, furnace brazing. The connection portion 120 has a layer of brazing material 50 formed between the inner circumferential surface 31 of the reinforcing member 30 and the outer circumferential surface 12 of the first connection portion 10. The reinforcing member 30 and the first connection portion 10 are joined by the first brazing material layer 51 formed between the inner circumferential surface 31 and the outer circumferential surface 12. In other words, in the refrigerant piping 110 of this embodiment, the reinforcing member 30 is made of stainless steel (metal) and is brazed to the first connection portion 10 with brazing material 50.

[0050] As shown in Figure 2, the connecting portion 120 is constructed by inserting the second connecting portion 20 into the first flared portion 15a on the upper side (one side in the axial direction) of the first connecting portion 10 from the upper side (one side in the axial direction), and manually brazing the inner circumferential surface 11 of the first connecting portion 10 and the outer circumferential surface 22 of the second connecting portion 20 using a burner. The connecting portion 120 has a layer of brazing material 50 formed between the inner circumferential surface 11 of the first connecting portion 10 and the outer circumferential surface 22 of the second connecting portion 20. In this description, the layer of brazing material 50 formed by manual brazing is referred to as the second brazing layer 52. The first connecting portion 10 and the second connecting portion 20 are joined by the second brazing layer 52 formed between the inner circumferential surface 11 and the outer circumferential surface 22. In this embodiment of the connecting portion 120, different brazing materials 50 are used for the first brazing layer 51 and the second brazing layer 52, respectively. The first brazing layer 51 and the second brazing layer 52 may use the same brazing material 50.

[0051] As shown in Figure 2, in the refrigerant piping 110 of this embodiment, the connection portion 120 includes a first portion 121 and a second portion 122. The first portion 121 is the portion that radially overlaps with the first pipe 111 or the second pipe 112. The second portion 122 is the portion that does not radially overlap with the first pipe 111 and the second pipe 112. In the connection portion 120, the second portion 122 extends axially from both axial ends of the first portion 121. In the refrigerant piping 110 of this embodiment, the reinforcing member 30 is arranged to cover the outer circumferential surface 123 of the second portion 122 (i.e., the outer circumferential surface 12 of the straight pipe portion 14 of the first connection portion 10).

[0052] If the second portion 122, which does not overlap radially with the first pipe 111 and the second pipe 112, is composed only of the first connection portion 10 (straight pipe portion 14), there is a concern that its pressure resistance strength may be insufficient. In this embodiment, the refrigerant piping 110 can improve the pressure resistance strength of the connection portion 120 in the second portion 122 by arranging a reinforcing member 30 on the radially outer side of the second portion 122.

[0053] As shown in Figure 2, in this embodiment, the refrigerant piping 110 has a radial thickness D of the second portion 122 that is less than or equal to the radial thickness DP1 of the first pipe 111, and less than or equal to the radial thickness DP2 of the second pipe 112 (D≦DP1, D≦DP2). In other words, in this embodiment, the refrigerant piping 110 has a connection portion 120 having the second portion 122, which is constructed using a thin copper pipe. In this case, the pressure resistance strength of the connection portion 120 can be ensured while using inexpensive copper pipes that have been commonly used as refrigerant piping. This makes it possible to reduce the manufacturing cost of the refrigerant piping 110 with improved pressure resistance.

[0054] Furthermore, a refrigeration system 100 (see Figure 1) having a refrigerant piping 110 with such a configuration can use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide, by using refrigerant piping 110 in which the pressure resistance strength of the connection portion 120 is improved by the reinforcing member 30.

[0055] [Regarding brazing methods for refrigerant piping] Figure 5 is a schematic cross-sectional view illustrating the state of the connection portion of the refrigerant piping (during brazing) according to the embodiment of this disclosure. Here, the brazing method of the connection portion 120 in the refrigerant piping 110 will be described. As shown in Figure 5, when brazing the refrigerant piping 110, the second connection portion 20 is inserted through the first flare portion 15a of the first connection portion 10 from above (one side in the axial direction), and the first pipe 111 and the second pipe 112 are arranged so that the central axes C1 and C2 are coaxial. In the refrigerant piping 110, the central axis C of the refrigerant piping 110 coincides with the central axis C1 of the first pipe 111 and the central axis C2 of the second pipe 112.

[0056] As shown in Figures 2 and 5, in the refrigerant piping 110 of this embodiment, the second connection portion 20 is connected to the first flare portion 15a. With this configuration, when connecting the second connection portion 20 to the first connection portion 10, the flare portion 15 (first flare portion 15a) allows the second connection portion 20 to be positioned in the axial direction.

[0057] Next, in this state, molten brazing material 50 is inserted into the gap between the inner circumferential surface 11 and the outer circumferential surface 22 to form a second brazing material layer 52 in the gap. This allows the first pipe 111 having the first connection part 10 and the second pipe 112 having the second connection part 20 to be brazed by hand.

[0058] As shown in Figures 2 to 5, the refrigerant piping 110 includes a first pipe 111 made of stainless steel and having a first end 113, a second pipe 112 made of stainless steel and having a second end 114, a first connecting part 10 made of copper and joined to the first end 113, a second connecting part 20 made of copper and joined to the second end 114, a connecting part 120 connecting the first end 113 and the second end 114, and a reinforcing member 30 arranged on the outer circumferential surface 123 of the connecting part 120. The connecting part 120 includes a first portion 121 that overlaps radially with the first pipe 111, and a second portion 122 that extends upward from the first portion 121 and does not overlap radially with the first pipe 111 and the second pipe 112.

[0059] As shown in Figure 2, in this embodiment, the refrigerant piping 110 has an axial length L2 of the second portion 122 that is greater than the axial length L1 of the first portion 121 (L2 > L1). Generally, the brazing material used to join copper pipes adheres to the copper pipes but not to stainless steel pipes. Therefore, if the brazing material that has penetrated into the refrigerant piping reaches the stainless steel pipe portion, the brazing material that peels off from the stainless steel pipe may circulate within the refrigerant circuit, potentially causing the refrigeration system to malfunction. For this reason, the brazing material that has penetrated into the refrigerant piping needs to be fixed to the copper pipe. The second portion 122, which is made of copper, has the function of fixing the brazing material 50 that has penetrated into the refrigerant piping 110. In this embodiment, the refrigerant piping 110 has an axial length L2 of the second portion 122 that is greater than the axial length L1 of the first portion 121, and by ensuring a sufficient axial length L2 of the second portion 122, the brazing material 50 that has entered the refrigerant piping 110 can be reliably fixed to the second portion 122. In this case, it is possible to suppress the diffusion of the brazing material 50 that has entered the refrigerant piping 110 into each part of the refrigerant circuit 103 (see Figure 1).

[0060] As shown in Figure 5, in this embodiment, the brazing method for the refrigerant piping 110 involves positioning the first pipe 111 with its first end 113 facing upwards and the second pipe 112 with its second end 114 facing downwards, and then brazing the inner circumferential surface 11 of the upper first end 13a of the first connection part 10 and the outer circumferential surface 22 of the lower second end 23b of the second connection part 20. When this brazing method is adopted, the second part 122 is connected to the first connection part 10 and the second connection part 20, thereby allowing the function of fixing the brazing material 50 to the second part 122 to be fully performed. With this brazing method, stainless steel refrigerant piping 110 with sufficient pressure resistance to use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide can be brazed manually.

[0061] If the brazing method for the refrigerant piping 110 of this embodiment is adopted, even if the brazing material 50 penetrates into the interior of the refrigerant piping 110 through the gap between the first connection part 10 and the second connection part 20, the penetrated brazing material 50 will be fixed to the inner circumferential surface 11 of the second part 122 located below the gap. Therefore, according to the brazing method of this embodiment, the second part 122 of the connection part 120 can suppress the dripping of the brazing material 50 that has penetrated into the interior of the refrigerant piping 110.

[0062] [Effects of the Embodiment] (1) The refrigerant piping 110 of this embodiment constitutes the refrigerant circuit 103 of the refrigeration device 100 and is a refrigerant piping 110 through which a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide flows. The refrigerant piping 110 includes a first pipe 111 made of stainless steel and having a first end 113, a second pipe 112 made of stainless steel and having a second end 114, a first connecting part 10 made of a material other than stainless steel and joined to the first end 113, and a second connecting part 20 made of the same material as the first connecting part 10 and joined to the second end 114. The refrigerant piping 110 of this embodiment includes a connecting part 120 that connects the first pipe 111 and the second pipe 112, and a reinforcing member 30 arranged on the outer circumferential surface 123 of the connecting part 120.

[0063] In this configuration, the refrigerant piping 110 can improve the pressure resistance of the connection portion 120 with the reinforcing member 30. Therefore, with this configuration, the stainless steel refrigerant piping 110 can be made to have sufficient pressure resistance to use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide.

[0064] (2) In the refrigerant piping 110 of this embodiment, the connection portion 120 includes a first portion 121 that overlaps radially with the first pipe 111 or the second pipe 112, and a second portion 122 that extends axially from the first portion 121 and does not overlap radially with the first pipe 111 and the second pipe 112. In the refrigerant piping 110 of this embodiment, the reinforcing member 30 is arranged on the outer circumferential surface 123 of the second portion 122.

[0065] In this configuration, the refrigerant piping 110 can improve the pressure resistance of the second portion 122, which does not overlap radially with the first pipe 111 and the second pipe 112 and therefore has lower pressure resistance.

[0066] (3) In the refrigerant piping 110 of this embodiment, the first connection part 10 and the second connection part 20 are made of copper, the first connection part 10 and the second connection part 20 are joined via a brazing material 50, the first connection part 10 and the second connection part 20 are made of copper, and the axial length L2 of the second part 122 is greater than the axial length L1 of the first part 121 (L2 > L1).

[0067] The second portion 122, which is made of copper, has the function of fixing the brazing material 50 that has penetrated into the refrigerant piping 110. In this embodiment, the refrigerant piping 110 can be reliably fixed to the second portion 122 by making the axial length L2 of the second portion 122 larger than the axial length L1 of the first portion 121.

[0068] (4) In the refrigerant piping 110 of this embodiment, the first connection part 10 and the second connection part 20 are made of copper, and the radial thickness D of the second part 122 is less than or equal to the radial thickness DP1 of the first pipe 111 and less than or equal to the radial thickness DP2 of the second pipe 112 (D≦DP1, D≦DP2).

[0069] In this configuration, the refrigerant piping 110 can have a connection section 120 having a second section 122, which can be made of a thin copper pipe. In this case, the pressure resistance of the connection section 120 can be ensured while using an inexpensive, thin copper pipe. This makes it possible to reduce the cost of the refrigerant piping 110 with improved pressure resistance.

[0070] (5) In this embodiment, the refrigerant piping 110 has a first end 113 in the first pipe 111 that opens toward one side in the axial direction, and a second end 114 in the second pipe 112 that opens toward the other side in the axial direction. In this embodiment, the refrigerant piping 110 has a first connection portion 10 that has a second portion 122 that extends toward one side in the axial direction from the first portion 121, and the inner circumferential surface 11 on one side in the axial direction of the first connection portion 10 and the outer circumferential surface 22 on the other side in the axial direction of the second connection portion 20 are joined by brazing material 50.

[0071] In this configuration, the refrigerant piping 110 can fix the brazing material 50 that has penetrated into the interior of the refrigerant piping 110 from between the inner circumferential surface 11 on one axial side of the first connection part 10 and the outer circumferential surface 22 on the other axial side of the second connection part 20 to the second part 122. This prevents the brazing material 50 that has penetrated into the interior of the refrigerant piping 110 from reaching the stainless steel first pipe 111 and second pipe 112.

[0072] (6) In the refrigerant piping 110 of this embodiment, the first connection part 10 has a flared portion 15 formed at one end on the axial side, and the second connection part 20 is connected to the flared portion 15.

[0073] In this configuration of refrigerant piping 110, the flared portion 15 allows the second connection portion 20 to be positioned when connecting the first connection portion 10 to the second connection portion 20.

[0074] (7) In the refrigerant piping 110 of this embodiment, the reinforcing member 30 is made of metal and is joined to the first connection part 10.

[0075] In this configuration, the refrigerant piping 110 can improve the pressure resistance of the connection portion 120 with the reinforcing member 30. With this configuration, the stainless steel refrigerant piping 110 can be made to have sufficient pressure resistance to use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide.

[0076] (8) In the refrigerant piping 110 of this embodiment, the reinforcing member 30 is made of stainless steel.

[0077] With a refrigerant piping 110 configured in this way, the pressure resistance strength of the reinforcing member 30 can be ensured, thereby improving the pressure resistance strength of the connection portion 120.

[0078] (9) The refrigeration system 100 of this embodiment is equipped with refrigerant piping 110.

[0079] In a refrigeration system 100 with this configuration, by using refrigerant piping 110 in which the pressure resistance strength of the connection part 120 is improved by the reinforcing member 30, it is possible to use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide.

[0080] (10) The brazing method for the refrigerant piping 110 of this embodiment is a brazing method for the refrigerant piping 110 comprising: a first pipe 111 made of stainless steel and having a first end 113; a second pipe 112 made of stainless steel and having a second end 114; a first connecting part 10 made of a material other than stainless steel (copper in this embodiment) and joined to the first end 113; a second connecting part 20 made of the same material other than stainless steel (copper in this embodiment) and joined to the second end 114; a connecting part 120 connecting the first end 113 and the second end 114; and a reinforcing member 30 arranged on the outer peripheral surface 123 of the connecting part 120. In the brazing method for the refrigerant piping 110 of this embodiment, the connection portion 120 includes a first portion 121 that overlaps radially with the first pipe 111, and a second portion 122 that extends upward from the first portion 121 and does not overlap radially with the first pipe 111 and the second pipe 112. The axial length L2 of the second portion 122 is made greater than the axial length L1 of the first portion 121. With the first pipe 111 positioned so that its first end 113 faces upward, and the second pipe 112 positioned so that its second end 114 faces downward, the inner circumferential surface 11 of the upper end 13a of the first connection portion 10 and the outer circumferential surface 22 of the lower end 23b of the second connection portion 20 are brazed together.

[0081] The brazing method for refrigerant piping 110 in this embodiment allows for manual brazing of stainless steel refrigerant piping 110 that has sufficient pressure resistance to use high-pressure refrigerants such as a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide. With this brazing method for refrigerant piping 110, the second part 122 can suppress the dripping of brazing material 50 that has penetrated into the interior of the refrigerant piping 110.

[0082] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Explanation of symbols]

[0083] 10: First connection section 11: Inner surface 12: Outer surface 13: End 15: Flare section 20: Second connection section 22: Outer surface 23: End 30: Reinforcement member 50: Brazing material 100: Refrigeration equipment 103: Refrigerant Circuit 110: Refrigerant piping 111: First piping 112: Second piping 113: First end 114:Second end 120: Connection part 121 :1st part 122:Second part 123: Outer surface L1: Axial length (of the first connection) L2: Axial length (of the second connection) D: Radial thickness (of the second part) DP1: Radial thickness (of the first connection) DP2: Radial thickness (of the second connection)

Claims

1. A refrigerant piping (110) that constitutes the refrigerant circuit (103) of a refrigeration device (100), through which a single refrigerant consisting of carbon dioxide or a mixed refrigerant containing carbon dioxide flows, A first pipe (111) made of stainless steel and having a first end (113), A second pipe (112) made of stainless steel and having a second end (114), It includes a first connecting portion (10) made of a material other than stainless steel and joined to the first end (113), a second connecting portion (20) made of the same material as the first connecting portion (10) and joined to the second end (114), and a connecting portion (120) that connects the first end (113) and the second end (114), The connection portion (120) is a refrigerant pipe (110) having a reinforcing member (30) positioned on the outer circumferential surface (123) of the connection portion (120).

2. The connecting portion (120) includes a first portion (121) that radially overlaps with the first pipe (111) or the second pipe (112), and a second portion (122) that extends axially from the first portion (121) and does not radially overlap with the first pipe (111) and the second pipe (112). The refrigerant piping (110) according to claim 1, wherein the reinforcing member (30) is arranged on the outer circumferential surface (123) of the second portion (122).

3. The first connecting portion (10) and the second connecting portion (20) are made of copper. The first connecting portion (10) and the second connecting portion (20) are joined together via brazing material (50). The refrigerant piping (110) according to claim 2, wherein the axial length (L2) of the second portion (122) is greater than the axial length (L1) of the first portion (121).

4. The first connecting portion (10) and the second connecting portion (20) are made of copper. The refrigerant piping (110) according to claim 2, wherein the radial thickness (D) of the second portion (122) is less than or equal to the radial thickness (DP1, DP2) of the first piping (111) and the second piping (112).

5. In the first pipe (111), the first end (113) opens toward one side in the axial direction, In the second pipe (112), the second end (114) opens toward the other axial direction, The first connecting portion (10) has a second portion (122) that extends from the first portion (121) in one axial direction, The refrigerant piping (110) according to claim 3, wherein the inner circumferential surface (11) on one axial side of the first connecting portion (10) and the outer circumferential surface (22) on the other axial side of the second connecting portion (20) are joined by the brazing material (50).

6. The first connecting portion (10) has a flared portion (15) formed at one end on the axial side, The refrigerant piping (110) according to claim 1 or claim 2, wherein the second connection portion (20) is connected to the flared portion (15).

7. The refrigerant piping (110) according to claim 1 or claim 2, wherein the reinforcing member (30) is made of metal and is joined to the first connecting portion (10).

8. The refrigerant piping (110) according to claim 7, wherein the reinforcing member (30) is made of stainless steel.

9. A refrigeration device (100) comprising the refrigerant piping (110) described in claim 1 or claim 2.

10. A first pipe (111) made of stainless steel and having a first end (113), A second pipe (112) made of stainless steel and having a second end (114), A first connecting portion (10) made of a material other than stainless steel having a tensile strength lower than that of stainless steel and joined to the first end (113), and a second connecting portion (20) made of the same material other than stainless steel and joined to the second end (114), are included, and a connecting portion (120) connecting the first end (113) and the second end (114), A reinforcing member (30) is positioned on the outer circumferential surface (123) of the connecting portion (120), A brazing method for refrigerant piping (110) equipped with, The aforementioned connecting portion (120) is The first pipe (111) includes a first portion (121) that overlaps radially with the first pipe (111), and a second portion (122) that extends upward from the first portion (121) and does not overlap radially with the first pipe (111) and the second pipe (112). The axial length (L2) of the second portion (122) is made greater than the axial length (L1) of the first portion (121). A method for brazing a refrigerant pipe (110), wherein the first pipe (111) is positioned with the first end portion (113) facing upward, and the second pipe (112) is positioned with the second end portion (114) facing downward, and the inner circumferential surface (11) of the upper end portion (13a) of the first connection portion (10) and the outer circumferential surface (22) of the lower end portion (23b) of the second connection portion (20) are brazed together.

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