Steel three-way connecting piece and refrigeration pipe assembly

Abstract

The utility model provides a steel three-way connecting piece and a refrigeration pipe assembly. The steel three-way connecting piece comprises a main pipe, a connecting piece and a connecting pipe. The main pipe is a thin-wall circular pipe fitting, a plastic protruding part extending towards the outer portion of the main pipe is formed on the peripheral wall of the main pipe through metal plastic forming, and a welding plane roughly parallel to the axis of the main pipe or obliquely distributed relative to the axis of the main pipe is formed at the tail end of the plastic protruding part. The welding plane is basically flush with or extends through the highest generatrix of the main pipe in the extending direction of the plastic protruding part, and a fluid through hole is formed in the welding plane. The connecting piece is welded to the welding plane in an attached mode, and a pipe connecting hole communicated with the fluid through hole is formed in the connecting piece. The connecting pipe is a thin-wall circular pipe fitting, and the connecting pipe is connected and welded to the connecting pipe hole in the connecting piece and / or the fluid through hole in the welding plane in a sleeved mode.

Description

Technical Field

[0001] The utility model relates to the field of refrigeration system accessories, and in particular to a steel three-way connector and a refrigeration pipe assembly. Background Art

[0002] The three-way connector is a common component in the refrigeration system, which is mainly used to connect the system pipelines to achieve the distribution of refrigerant. Existing three-way connectors are mostly made of copper material, and copper is a precious metal material. As its market price continues to rise, the cost of copper three-way connectors is also getting higher and higher. Therefore, the development of three-way connectors using low-cost steel materials instead of copper materials has become a research and development direction for technicians in this field. The ductility of steel is only about 20% of that of copper, but its hardness is 4 to 5 times that of copper. Such physical properties make it difficult for steel materials to directly form or punch and flanging the pipe welding connection length that meets the brazing requirements like copper materials. Therefore, the pipe 700 in the existing steel three-way connector can only be welded to the intersecting line hole 601 on the main pipe 600 by means of a self-fluxing curved line weld (such as Figure 1 Obviously, the pressure resistance of the steel three-way connector formed by this welding method will be difficult to meet the high design working pressure requirements of the refrigeration system.

[0003] In order to solve the problem that the existing self-fluxing welded steel three-way connector is difficult to be applied to the refrigeration system, the inventor proposed a steel three-way connector with excellent pressure resistance in Chinese patent CN2024205048701 (application date March 15, 2024). In this structure, a pipe hole is opened on the outer peripheral wall of the steel connector, and the wall thickness T of the steel connector at the pipe hole is controlled to form a large area of ​​brazing surface on the inner peripheral wall of the pipe hole, thereby achieving the connection strength and pressure resistance of the pipe after brazing to meet the requirements of the refrigeration system. However, the large area of ​​brazing surface is achieved based on the wall thickness T of the steel connector; therefore, the wall thickness of the steel connector should be thicker. The large wall thickness will not only greatly increase the material cost of the steel connector, but also increase its processing difficulty and energy consumption during the processing. Furthermore, in order to realize the opening of the pipe hole, the outer peripheral wall of the steel connector needs to form a brazing plane to provide a hole opening reference for the opening of the pipe hole. However, due to the limitation of wall thickness, steel connectors can only be processed by hot forging or cold heading combined with machining to form a structure with a polygonal cross-section or a structure with one side as a welding plane and other areas still as arc surfaces; this processing method is not only complicated but also has high processing energy consumption.

[0004] In addition, the inventor also proposed a new steel three-way pipe fitting in Chinese patent CN2024205048453 (application date March 15, 2024). This structure forms a large brazing surface in the pipe hole by adding an inner sleeve to the thin-walled pipe body or by controlling the wall thickness of the main pipe body at the pipe hole. Similarly, whether it is the increase in the wall thickness of the main pipe body or the setting of the inner sleeve, it will bring great pressure to the material cost of the three-way pipe fitting, and the assembly of the inner sleeve and the processing of the pipe hole on the thick-walled main pipe body are also relatively complicated. Utility Model Content

[0005] In order to overcome the deficiencies of the prior art, the utility model provides a steel three-way connector and a refrigeration pipe assembly.

[0006] In order to achieve the above-mentioned purpose, the utility model provides a steel three-way connector, which includes a main pipe, a connector and a connecting pipe. The main pipe is a thin-walled circular pipe, and a plastic protrusion extending to the outside of the main pipe is formed on the peripheral wall of the main pipe by metal plastic forming, and a welding plane is formed at the end of the plastic protrusion, which is roughly parallel to the axis of the main pipe or inclined relative to the axis of the main pipe, and the welding plane is basically flush with or extends over the highest generatrix of the main pipe in the extension direction of the plastic protrusion, and a fluid through hole is opened on the welding plane. The connector is welded to the welding plane, and a connecting pipe hole connected to the fluid through hole is opened on the connector. The connecting pipe is a thin-walled circular pipe, and the connecting pipe is welded to the connecting pipe hole on the connector and / or the fluid through hole on the welding plane.

[0007] According to an embodiment of the utility model, the cross-sectional area of ​​the plastic protrusion gradually increases along its extension direction, and the area of ​​the region enclosed by the outer contour line of the welding plane is greater than or equal to the inner hole cross-sectional area of ​​the non-plastic protrusion region on the main pipe.

[0008] According to an embodiment of the present invention, the projection surface of the welding plane in the extension direction of the plastic protrusion is any one of a circle, an ellipse or a polygon.

[0009] According to an embodiment of the utility model, the welding plane includes the terminal outer surface and / or the terminal inner surface of the plastic protrusion, and the connecting piece includes one or more combinations of a circular connecting tube, a sheet lining plate or a flange seat.

[0010] According to an embodiment of the utility model, the connecting piece includes a sheet-like lining plate or a plurality of sheet-like lining plates stacked in sequence and welded on a welding plane, and the sheet-like lining plate is a polygonal lining plate or an annular lining plate having a circular pipe hole.

[0011] According to an embodiment of the present utility model, the flanging seat includes a flanging tabletop and a flanging portion. The flanging portion surrounds the outer edge of the connecting pipe hole and is connected to the flanging tabletop. The flanging tabletop is adhesively welded to the welding plane formed on the outer surface of the end of the plastic bulge portion or adhesively welded to the sheet-shaped lining plate. The connecting pipe is socket-welded to the flanging portion.

[0012] According to an embodiment of the present utility model, a self-fusion weld seam and / or a brazed weld seam for fixing the connecting member are formed between the connecting member and the welding plane. The self-fusion weld seam is a partial weld seam or an integral circumferential weld seam.

[0013] According to an embodiment of the present utility model, the main pipe is a straight pipe with both ends open. The plastic bulge portion inclines or vertically protrudes from the peripheral wall of the main pipe to one side of the main pipe. The two ends of the main pipe and the connecting pipe together form the three connecting pipe ends of the steel three-way connecting member.

[0014] According to an embodiment of the present utility model, the main pipe is a bent pipe with both ends open and the two ends of the bent pipe face different directions. The plastic bulge portion protrudes and extends outward from the bending portion of the main pipe. The welding plane located at the end of the plastic bulge portion is substantially parallel to the axis of the bending portion of the main pipe or is inclined relative to the axis of the bending portion of the main pipe. The two ends of the main pipe and the connecting pipe together form the three connecting pipe ends of the steel three-way connecting member;

[0015] Or, the main pipe is a bent pipe with both ends open and the two ends of the bent pipe face substantially the same direction. The plastic bulge portion protrudes and extends outward from the bending portion of the main pipe. The welding plane located at the end of the plastic bulge portion is substantially parallel to the axis of the bending portion of the main pipe. The two ends of the main pipe and the connecting pipe together form the three connecting pipe ends of the steel three-way connecting member.

[0016] According to an embodiment of the present utility model, the main pipe has a single-end open structure. At least two plastic bulge portions protruding respectively to both sides of the axis of the main pipe are formed on the peripheral wall of the main pipe. A welding plane is formed at the end of each plastic bulge portion, and a fluid through hole is provided on each welding plane. Two connecting members are respectively adhesively welded to two of the welding planes, and a connecting pipe hole with an axis axially intersecting the open end of the main pipe at an angle close to a right angle or an obtuse angle is provided on each connecting member. The two connecting pipes connected to the two connecting pipe holes and the open end of the main pipe together form the three connecting pipe ends of the steel three-way connecting member.

[0017] According to an embodiment of the present utility model, the main pipe is a single-end open tensile cylinder; or the main pipe includes a thin-walled pipe body with both ends open and an end cover for blocking one of the open ends of the thin-walled pipe body.

[0018] The present utility model further provides another steel three-way connector, which includes a steel main pipe, a connector, and a connecting pipe. The main pipe is a thin-walled circular pipe fitting with an open end at one end. A plastic bulge extending outward from the main pipe is formed on the peripheral wall of the main pipe by metal plastic forming. The outer wall of the plastic bulge near the closed end of the main pipe is substantially flush with the outer end wall of the closed end of the main pipe and together with the outer end wall of the closed end of the main pipe forms a welding plane. Two fluid through holes are provided on the welding plane. The connector is welded to the welding plane, and two connecting pipe holes communicating with the two fluid through holes respectively are provided on the connector. The two connecting pipes are thin-walled circular pipe fittings, and the two connecting pipes are respectively sleeved and welded to the two connecting pipe holes on the connector and / or the fluid through holes on the corresponding welding plane.

[0019] According to an embodiment of the present utility model, the welding plane is elliptical or polygonal, and the width of the welding plane in the arrangement direction of the two fluid through holes is greater than the width in another direction perpendicular to the arrangement direction.

[0020] On the other hand, the present utility model further provides a refrigeration pipe assembly, which includes the steel three-way connector according to any one of the above.

[0021] In summary, in the steel three-way connector provided by the present utility model, a plastic bulge extending outward from the main pipe is formed on the thin-walled circular main pipe by metal plastic forming. The end of the plastic bulge forms a welding plane to realize the surface fitting welding of the connector, and the connecting pipe is sleeved and connected to the connecting pipe hole on the connector and / or the fluid through hole on the welding plane. In the present utility model, the plastic bulge does not provide the welding depth for the connecting pipe, and it is only used to form a welding plane for the surface fitting welding of the connector. Therefore, the deformation amount of the plastic bulge only needs to satisfy that the welding plane is substantially flush with or extends beyond the highest generatrix of the main pipe in the extending direction of the plastic bulge; this setting greatly reduces the difficulty of metal plastic processing of the steel main pipe and also effectively reduces the processing energy consumption. Further, in the steel three-way connector provided by the present utility model, the connecting pipe holes are no longer directly formed on the large-volume main pipe, but are formed on the relatively small-volume connector. Based on this setting, only by controlling the hole depth of the connecting pipe holes on the connector can the surface brazing connection of the connecting pipe be realized, so that the connection strength and pressure resistance after welding of the connecting pipe can meet the requirements of the refrigeration system; and the relatively large-volume main pipe can select thin-walled pipe fittings to greatly reduce the material cost of the steel three-way connector, and the thin-walled main pipe is also more conducive to the forming of the plastic bulge.

[0022] To make the above and other objects, features, and advantages of the present utility model more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the accompanying drawings, makes the following detailed description. Description of the Drawings

[0023] Figure 1 The figure shows a structural schematic diagram of an existing steel three-way connector.

[0024] Figure 2 The following is a schematic structural diagram of the steel three-way connector provided in the first embodiment of the present utility model.

[0025] Figure 2A The following shows Figure 2 a schematic structural diagram from another perspective.

[0026] Figure 3 The following shows Figure 2 a schematic cross-sectional diagram of

[0027] Figure 3A The following shows Figure 3 an enlarged schematic diagram of part A in

[0028] Figure 4 The following shows Figure 2 a schematic structural diagram of the main pipe in

[0029] Figure 4A The following shows Figure 4 a schematic structural diagram from another perspective.

[0030] Figure 4B The following shows Figure 4 a schematic cross-sectional diagram of

[0031] Figure 5 The following shows Figure 2 a schematic structural diagram of the sheet-shaped lining plate as the connector in

[0032] Figure 5A The following is a schematic structural diagram of the sheet-shaped lining plate provided in another embodiment of the present utility model.

[0033] Figure 6A and Figure 6B The following shows a schematic structural diagram of the connector provided in another embodiment.

[0034] Figure 7 The following is a schematic structural diagram of the steel three-way connector provided in another embodiment of the present utility model.

[0035] Figure 7A The following shows Figure 7 an enlarged schematic diagram of part B in

[0036] Figure 8 The following shows Figure 7 a schematic structural diagram of the main pipe in

[0037] Figure 8A The following shows Figure 8 a schematic structural diagram from another perspective.

[0038] Figure 9 The following is a schematic structural diagram of the refrigeration pipe assembly provided in the first embodiment of the present utility model.

[0039] Figure 10 Shown is a schematic structural view of the steel three-way connector provided in the second embodiment.

[0040] Figure 11 Shown is Figure 10 a schematic cross-sectional view of

[0041] Figure 12 Shown is Figure 10 a schematic structural view of the main pipe in

[0042] Figure 12A Shown is Figure 12 a schematic structural view from another perspective.

[0043] Figure 13 Shown is Figure 12 a schematic cross-sectional view of the main pipe in

[0044] Figure 14 Shown is a schematic structural view of the steel three-way connector provided in another embodiment of the present utility model.

[0045] Figure 15 Shown is a schematic structural view of the steel three-way connector with a tapered closed end of the main pipe provided in another embodiment of the present utility model.

[0046] Figure 15A Shown is Figure 15 a schematic cross-sectional view of

[0047] Figure 15B Shown is Figure 15 a schematic structural view of the main pipe 1 in

[0048] Figure 16 Shown is a schematic structural view of the steel three-way connector with a quadrangular pyramid-shaped closed end of the main pipe provided in another embodiment of the present utility model.

[0049] Figure 16A Shown is Figure 16 a schematic structural view of the main pipe in

[0050] Figure 16B Shown is Figure 16A a schematic structural view from another perspective.

[0051] Figure 16C It is Figure 16A a schematic structural view of the main pipe shown before metal plastic forming.

[0052] Figure 17 Shown is a schematic structural view of the steel three-way connector with the closed end of the main pipe recessed towards the open end.

[0053] Figure 17A Shown is Figure 17 a schematic cross-sectional view of

[0054] Figure 17B Shown is Figure 17 the structural schematic diagram of the main pipe 1 in the middle.

[0055] Figure 18 Shown is the assembly schematic diagram of the main pipe and the connector in the steel three-way connector provided by another embodiment of the present utility model.

[0056] Figure 19 Shown is Figure 18 the structural schematic diagram of the main pipe in the middle.

[0057] Figure 20A Shown is the structural schematic diagram of the main pipe in the steel three-way connector provided by another embodiment of the present utility model.

[0058] Figure 20B Shown is the structural schematic diagram of the steel three-way connector provided by another embodiment of the present utility model.

[0059] Figure 20C It is Figure 20B the structural schematic diagram of the main pipe in the middle.

[0060] Figure 20D It is Figure 20C the structural schematic diagram from another perspective.

[0061] Figure 21 Shown is the structural schematic diagram of the refrigeration pipe assembly provided by Embodiment 2 of the present utility model.

[0062] Figure 22 Shown is the structural schematic diagram of the refrigeration pipe assembly provided by another embodiment of the present utility model.

[0063] Figure 23 Shown is the structural schematic diagram of the steel three-way connector provided by Embodiment 3 of the present utility model.

[0064] Figure 23A Shown is Figure 23 the structural schematic diagram from another perspective.

[0065] Figure 24 Shown is Figure 23 the sectional schematic diagram of...

[0066] Figure 25 Shown is Figure 23 the structural schematic diagram of the main pipe in the middle.

[0067] Figure 25A It is Figure 25 the structural schematic diagram from another perspective.

[0068] Figure 26The following is a schematic structural view of the main pipe in the steel three-way connector provided by another embodiment of the present utility model.

[0069] Figure 27 and Figure 28 The following is a schematic structural view of the refrigeration pipe assembly provided by another embodiment of the present utility model.

[0070] Figure 29 The following is a schematic structural view of the steel three-way connector provided by the fourth embodiment of the present utility model.

[0071] Figure 30 The following is a schematic structural view of the steel three-way connector provided by another embodiment of the present utility model.

[0072] Figure 31 The following is a schematic structural view of the steel three-way connector provided by the fifth embodiment of the present utility model.

[0073] Figure 31A The following is Figure 31 a schematic structural view from another perspective.

[0074] Figure 32 The following is Figure 31 a schematic sectional view.

[0075] Figure 32A It is Figure 32 an enlarged schematic view of part C in

[0076] Figure 33 The following is Figure 31 a schematic structural view of the main pipe in

[0077] Figure 34 The following is Figure 33 a partial schematic sectional view of

[0078] Figure 35 The following is a schematic structural view of the refrigeration pipe assembly provided by the fifth embodiment of the present utility model.

[0079] Figure 36 The following is a schematic structural view of the steel three-way connector provided by the sixth embodiment of the present utility model.

[0080] Figure 36A The following is Figure 36 a partial schematic sectional view of

[0081] Figure 37 The following is Figure 36 a schematic sectional view of the main pipe in

[0082] Figure 37A The following is Figure 37 an enlarged schematic view of part E in

[0083] Figure 37B Shown Figure 36 Schematic diagram of the structure of the central tube from another perspective.

[0084] Figure 38 Shown is a schematic structural diagram of a steel three-way connector provided in another embodiment of the present invention.

[0085] Figure 38A Shown Figure 38 Schematic diagram of the structure of the central supervisor.

[0086] Figure 39 Shown is a partial cross-sectional schematic diagram of a steel three-way connector provided in another embodiment of the utility model.

[0087] Figure 40 Shown is a schematic structural diagram of a refrigeration tube assembly provided in Embodiment 5 of the present utility model.

[0088] Figure 41 Shown is a schematic structural diagram of a steel three-way connector provided in Example 7 of the present utility model.

[0089] Figure 42 Shown Figure 41 Schematic diagram of the structure of the central supervisor.

[0090] Figure 43 Shown Figure 41 Schematic diagram of the structure of the integral sheet liner. DETAILED DESCRIPTION

[0091] Embodiment 1

[0092] like Figure 1 As shown in the figure, the traditional steel tee connectors that use self-melting wire welds for pipe welding are difficult to be used in refrigeration systems with high design pressure requirements due to the low connection strength and pressure resistance of the pipes. The steel tee pipe structure with thick-walled steel connectors, thick-walled main pipes or thin-walled main pipes combined with inner sleeves as the pipes, although the connection strength and pressure resistance of the pipes meet the requirements of the refrigeration system, has problems such as high material cost, greater processing difficulty and more complicated procedures.

[0093] In view of this, the present embodiment provides a low-cost, easy-to-process steel three-way connector that can use thin-walled pipes as main pipes and has pipe welding strength and pressure resistance that can meet the requirements of the refrigeration system. Figures 2 to 3AAs shown in the figure, the steel three-way connector 10 provided in this embodiment includes a main pipe 1, a connector 2, and a connecting pipe 3. The main pipe 1 is a thin-walled circular pipe fitting. A plastic convex part 11 extending outward from the main pipe is formed on the peripheral wall of the main pipe 1 by metal plastic forming. A welding plane 12 that is substantially parallel to the axis of the main pipe or is inclined relative to the axis of the main pipe is formed at the end of the plastic convex part 11. The welding plane 12 is basically flush with or extends beyond the highest generatrix K of the main pipe in the extending direction of the plastic convex part 11. A fluid through hole 121 is provided on the welding plane 12. The connector 2 is welded to the welding plane 12 and a connecting pipe hole 21 communicating with the fluid through hole is provided on the connector 2. The connecting pipe 3 is a thin-walled circular pipe fitting, and the connecting pipe 3 is socket-welded to the connecting pipe hole 21 on the connector 2 and / or the fluid through hole 121 on the welding plane 12.

[0094] In this embodiment, the thin-walled pipe fitting refers to a pipe fitting with a wall thickness greater than or equal to 0.2 mm and less than or equal to 2 mm, such as pipe fittings with wall thicknesses of 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, etc. However, the present utility model does not make any limitation thereto. In other embodiments, the wall thickness of the main pipe may also be any value within 0.2 mm to 2 mm.

[0095] Such as Figure 3 and Figure 3A As shown in the figure, in the steel three-way connector provided in this embodiment, the aperture of the fluid through hole 121 on the welding plane 12 is smaller than the aperture of the connecting pipe hole 21. The connecting pipe 3 is inserted into the connecting pipe hole 21 in a nested manner and the end face of its inserted end abuts against the welding plane 12. The welding plane 12 provides a limit for the insertion and assembly of the connecting pipe 3. The connecting pipe 3 communicates with the inner cavity of the main pipe 1 through the fluid through hole 121. In this embodiment, the front end of the connecting pipe 3 does not insert into the flow through hole 121, and the fluid through hole 121 only serves to connect the connecting pipe 3 and the main pipe 1. Therefore, the present utility model does not make any limitation to the shape of the fluid through hole, and it can be circular, elliptical or other structures. In other embodiments, it is also possible to set the shape and aperture of the fluid through hole to be the same as those of the connecting pipe hole, and the front end of the connecting pipe is socket-welded in the connecting pipe hole and the fluid through hole.

[0096] In this embodiment, the fluid through hole 121 is a through hole without a flanging part. However, the present utility model does not make any limitation thereto. In other embodiments, the fluid through hole may also be a flanging hole with a flanging part.

[0097] In the steel three-way connector provided in this embodiment, the connecting pipe 3 is not directly connected to the fluid through-hole 121 on the main pipe 1, but is brazed to the connecting pipe hole 21 on the connector 2, or is brazed to the connecting pipe hole 21 and the fluid through-hole 121; that is, the connecting pipe hole 21 on the connector 2 provides the welding depth for the connecting pipe 3. Based on this setting, during design, only the hole depth of the connecting pipe hole 21 on the connector 2 needs to be controlled to achieve the surface brazing connection of the connecting pipe 3, thereby ensuring that the connection strength and pressure resistance after welding of the connecting pipe 3 can meet the requirements of the refrigeration system. Compared with the connector 2, the main pipe 1 is not only longer in length but also larger in cross-sectional area, so the impact of the wall thickness on the material cost of the main pipe 1 will be much greater than that of the connector 2. The steel three-way connector provided in this embodiment forms the connecting pipe hole 21 in the relatively small-volume connector 2, so that the wall thickness of the relatively large-volume main pipe 1 is no longer restricted by the welding of the connecting pipe 3, and thus the main pipe 1 can adopt low-cost thin-wall steel pipe fittings to greatly reduce the material cost of the steel three-way connector.

[0098] The outer peripheral wall of the thin-wall circular main pipe 1 is an arc-shaped curved surface structure. To achieve the welded connection of the connector 2, it is usually necessary to set the welding end surface of the connector 2 as a curved surface structure with a curvature matching that of the outer peripheral wall of the main pipe 1, so that the welding gap after the two are fitted can meet the capillary penetration effect during brazing. However, affected by the roundness tolerance during the processing of the main pipe 1 and the surface profile tolerance of the welding end surface of the connector 2, the uniformity of the welding gap after the two are fitted and assembled is poor, resulting in difficulty for the solder to uniformly penetrate into the welding gap, and it is very easy to have welding problems such as false soldering and leakage after welding. Further, it is also difficult to ensure the consistency of the welding gaps between batch products, so there is also a problem of poor batch product consistency. To solve this problem, in the steel three-way connector provided in this embodiment, a plastically protruding portion 11 extending outward is formed on the peripheral wall of the main pipe 1 by metal plastic forming, and a welding plane 12 for carrying the connector 2 is formed at the end of the plastically protruding portion 11. The connector 2 is welded and connected to the brazing plane 12 in a plane-fitting manner. Compared with surface fitting, plane fitting only needs to control the flatness of the two fitting surfaces to make the welding gap after the two are assembled uniform and meet the brazing requirements. At the same time, the consistency of the welding gaps of batch products can also be accurately controlled. While ensuring that the connection strength and pressure resistance of the connector 2 after brazing meet the requirements of the refrigeration system, the qualified rate of the batch products after welding is also greatly improved, thus well solving the welding quality problem and the problem of poor batch consistency caused by the difficult accurate matching of the curvature during the surface welding between the connector and the main pipe. In addition, compared with surface fitting, plane fitting is not only more convenient for processing the fitting surfaces but also more conducive to positioning and assembly.

[0099] In the steel three-way connector provided in this embodiment, the plastic protrusion 11 does not provide welding depth for the connecting pipe 3. It is only used to form a welding plane 12 on the peripheral wall of the main pipe 1 to achieve planar welding of the connector 2. Therefore, the present invention does not impose any limitation on the amount of deformation of the plastic protrusion 11, as long as the welding plane is basically flush or extends beyond the highest generatrix of the main pipe 1 in the extending direction of the plastic protrusion 11 (such as Figure 3 and Figure 3A the dashed line K in, abbreviated as the highest generatrix K). This setting greatly reduces the difficulty of metal plastic processing of the main pipe, provides conditions for the main pipe to select a metal plastic process with mature processes and low energy consumption (such as hydroforming process) and low-cost steel pipe fittings; in addition, the thin-walled main pipe 1 is also more conducive to the metal plastic forming of the plastic protrusion 11.

[0100] Specifically, as shown in Figure 4 , Figure 4A and Figure 4B , the main pipe 1 is a straight pipe with both ends open, and the plastic protrusion 11 extends obliquely from the peripheral wall of the main pipe 1 to one side of the main pipe 1. The two ends of the main pipe 1 and the connecting pipe 3 together form the three connecting pipe ends of the steel three-way connector. The end of the plastic protrusion 11 forms a welding plane 12 that is obliquely distributed relative to the axis of the main pipe 1 and extends beyond the highest generatrix K on the main pipe 1. However, the present invention does not impose any limitation on this. In other embodiments, in order to further reduce the processing difficulty, improve the qualification rate of plastic forming and reduce the forming energy consumption, the welding plane can also be basically flush with the highest generatrix K or slightly extend beyond the highest generatrix K, and the welding plane can also be substantially parallel to the axis of the main pipe 1.

[0101] In this embodiment, as shown in Figure 4 , the projection plane of the welding plane 12 in the extending direction of the plastic protrusion 11 is circular. However, the present invention does not impose any limitation on this. In other embodiments, the projection plane of the welding plane in the extending direction of the plastic protrusion can also be oval, polygonal (such as square) or other special-shaped structures.

[0102] In this embodiment, the welding plane 12 is the outer surface of the end of the plastic protrusion 11. The connector 2 includes multiple stacked sheet liners 2a, and each sheet liner 2a is formed with a substantially coaxial liner hole 2a1. After multiple liner holes 2a1 are stacked, a connecting pipe hole 21 is formed. Specifically, after multiple sheet liners 2a are formed into an integral part by local self-fusion welding (such as multiple spot welds or multiple line welds), the innermost sheet liner 2a is pre-fixed to the welding plane 12 by local or circumferential self-fusion welds 101, such as Figure 3AAs shown in the figure; afterwards, the connecting pipe 3 is assembled into the connecting pipe hole 21; finally, the main pipe 1, the connecting member 2 including multiple sheet-shaped liners 2a, and the connecting pipe 3 are integrally welded by furnace brazing. Since the melting point of the weld formed by autogenous welding (which is the melting point of the steel material) is higher than the brazing temperature, during brazing, the innermost sheet-shaped liner 2a is stably connected to the welding plane 12 through the autogenous weld, and adjacent sheet-shaped liners 2a are also stably connected through the autogenous weld, effectively avoiding welding problems caused by the position deviation of the connecting member 2 during brazing.

[0103] After furnace brazing, as Figure 3 and Figure 3A shown, a first brazing weld 201 is formed between the outer peripheral wall of the insertion end of the connecting pipe 3 and the inner peripheral wall of the connecting pipe hole 21, a second brazing weld 202 is formed between the end face of the insertion end of the connecting pipe 3 and the welding plane 12, a third brazing weld 203 is formed between the innermost sheet-shaped liner 2a and the welding plane 12, and a fourth brazing weld 204 is also formed between adjacent sheet-shaped liners 2a. The third brazing weld 203 and the fourth brazing weld 204 make the connecting member 2 and the main pipe 1 form an integral body with high connection strength and high pressure resistance. Preferably, the minimum fitting width between the connecting member 2 (i.e., the innermost sheet-shaped liner 2a) and the welding plane 12 is not less than 1.5 mm to form a large-area third brazing weld 203 and fourth brazing weld 204, ensuring that the connecting member 2 has excellent connection strength and pressure resistance after brazing. However, the present utility model does not make any limitation in this regard. Specifically, the fitting width refers to the overlapping width of the welding plane 12 and the connecting member 2 in the radial direction of the fluid through hole 121.

[0104] In addition, for the connecting pipe 3, on the basis of forming the first brazing weld 201 on the inner peripheral wall of the connecting pipe hole 21, a second brazing weld 202 that is integrated with the first brazing weld 201 is also formed between the end face of the insertion end of the connecting pipe 3 and the welding plane 12. This setting further increases the brazing area of the connecting pipe 3 so that its connection strength and sealing performance after brazing can well meet the requirements of the refrigeration system. Although this embodiment is described by taking that there is an autogenous weld 101 and a third brazing weld 203 between the connecting member 2 and the welding plane 12 as an example. However, the present utility model does not make any limitation in this regard. In other embodiments, the connecting member can also be positioned on the welding plane by a tooling and then subjected to furnace brazing, and there can also be only a brazing weld between the connecting member and the welding plane without the need for an autogenous weld for pre-fixing. Similarly, there is no need for an autogenous weld for pre-fixing between adjacent sheet-shaped liners.

[0105] In this embodiment, as Figure 4AAs shown, the cross-sectional area of the plastic protrusion 11 gradually increases along its extending direction, and the area of the region enclosed by the outer contour line of the welding plane 12 is larger than the inner hole cross-sectional area of the non-plastic protrusion region 13 on the main pipe 1. This setting enables the welding plane 12 to provide a larger bearing area for the connecting member 2. While the aperture diameter of the connecting pipe hole 21 is close to the inner hole aperture diameter of the non-plastic protrusion region 13, it ensures that there is a brazing area that meets the welding strength between the connecting member 2 and the welding plane 12, thereby enabling the steel three-way connecting member provided in this embodiment to be an equal-diameter three-way or a near-equal-diameter three-way; or alternatively, the aperture diameter of the connecting pipe hole is larger than the inner hole aperture diameter of the non-plastic protrusion region. However, the present utility model does not make any limitation thereto. In other embodiments, if the aperture diameter of the connecting pipe hole is small, the area of the region enclosed by the outer contour line of the welding plane may also be set to be substantially close to the inner hole cross-sectional area of the non-plastic protrusion region on the main pipe.

[0106] In this embodiment, as Figure 5 shown, each sheet-shaped lining plate 2a is an annular lining plate having a circular lining plate hole 2a1, and a plurality of circular lining plate holes 2a1 form a circular connecting pipe hole 21 for welding and connecting the connecting pipe 3. However, the present utility model does not make any limitation thereto. In other embodiments, the sheet-shaped lining plate may also be other polygonal lining plates having circular lining plate holes, such as a square lining plate (as Figure 5A shown), a pentagonal lining plate, a hexagonal lining plate, etc.

[0107] Although this embodiment is described by taking the welding plane 12 as the inner surface of the end of the plastic protrusion 11 and the connecting member 2 including a plurality of sheet-shaped lining plates 2a as an example. However, the present utility model does not make any limitation thereto. In other embodiments, the welding plane may also be the outer surface of the end of the plastic protrusion; or it may include both the outer surface and the inner surface of the end of the plastic protrusion. The connecting member may also be disposed on the inner surface of the end of the plastic protrusion; or part of it is disposed on the inner surface of the end of the plastic protrusion, while part of it is disposed on the outer surface of the end of the plastic protrusion. Regarding the specific structure of the connecting member 2, in other embodiments, it may also only include a thick sheet-shaped lining plate. Or, as Figure 6A shown, the connecting member 2 is a circular connecting pipe, and the welding end 22 of the circular connecting pipe is planar (a parallel plane parallel to the axis of the main pipe or an inclined plane inclined relative to the axis of the main pipe) to fit the welding plane 12, and the pipe hole of the circular connecting pipe serves as the connecting pipe hole 21. Or, as Figure 6BAs shown, the connector 2 includes a flanged seat, the flanged seat includes a flanged table 23 and a flanged portion 24, the flanged portion 24 is arranged around the outer edge of the pipe hole 21 and connected to the flanged table 23, the flanged table 23 is welded to the welding plane 12, and the pipe 3 is welded to the flanged portion 24, and in this structure, the flanged portion 24 provides welding depth for the pipe 3. Alternatively, in other embodiments, the connector includes a combination of a circular connecting pipe, a sheet liner or a flanged seat; such as a combination of a circular connecting pipe and a sheet liner, or a combination of a flanged seat and a sheet liner; or a flanged seat and a circular connecting pipe, such as the flanged seat is welded to the inner surface of the end of the plastic protrusion, and the circular connecting pipe is welded to the outer surface of the end of the plastic protrusion.

[0108] In this embodiment, the main pipe 1, the connector 2 and the pipe 3 are all steel parts. In order to ensure the corrosion resistance of the key welding connection parts (such as the welding connection of the pipe 3), the steel parts are made of steel with a chromium (Cr) content of not less than 5% to improve the service life of the product. For example, stainless steel materials that are resistant to corrosion by weak corrosive media such as air, steam, water, and chemically corrosive media such as acids, alkalis, and salts are selected. Further, based on cost considerations, non-300 series stainless steel with a Cr content of not less than 5% is preferably used, such as SUS430 (commonly known as stainless iron, Cr% ≥ 16-18%) or SUS201 (Cr% ≥ 13%, Ni% ≥ 3.5%). For the stainless steel material of SUS201, the steel material with Cr% ≥ 10% and Ni% ≥ 1% produced by the "Qingshan Stainless Steel" manufacturer, and the wire grade D665A or D667, can be selected to take into account the material cost while meeting the requirements of environmental corrosion resistance and no rust. However, the utility model does not make any limitation to this. In other embodiments, the main pipe, the connecting piece and the connecting pipe may also be made of other steel materials with a Cr content of not less than 5% according to the application environment.

[0109] Figure 7 FIG. 1 is a schematic diagram of the structure of a steel three-way connector provided by another embodiment of the present invention. Figure 7A , Figure 8 as well as Figure 8A As shown, the welding plane 12 at the end of the plastic protrusion 11 is roughly parallel to the axis of the main pipe 1 and is basically flush with the highest generatrix K of the main pipe 1. The connecting piece 2 is a circular connecting pipe with an inclined plane at the welding end. The welding end of the connecting piece 2 is welded to the welding plane 12 and a self-melting weld and a brazing seam for fixing the connecting piece are formed between the connecting piece 2 and the welding plane 12. The pipe hole of the circular connecting pipe is used as a pipe hole 21 to weld and connect the pipe 3. In this structure, as shown in FIG. Figure 8 As shown, the projection of the welding plane 12 in the extension direction of the plastic protrusion 11 is elliptical, and the fluid through hole 121 formed on the welding plane is also elliptical. However, the present invention does not impose any limitation on this.

[0110] In the steel three-way connector provided by the utility model, the plastic convex part 11 does not provide welding depth for the connecting pipe 3, and it is only used to form the welding plane 12. Therefore, on the premise of satisfying that the welding plane 12 is basically flush or extends beyond the highest bus bar K of the main pipe 1, the shorter the extension length of the plastic convex part 11, the easier it is to form and the smaller the forming energy consumption will be.

[0111] Although this embodiment takes the two ends of the main pipe 1 and the connecting pipe 3 as the three connection ends of the steel three-way connector as an example for illustration. However, the utility model does not make any limitation thereto. In other embodiments, based on the requirements of the application scenario, two thin-walled end connecting pipes can also be welded to the two ends of the main pipe to extend the end connection length of the steel three-way connector; the end connecting pipes can be any one of steel pipe fittings or copper pipe fittings.

[0112] Correspondingly, as Figure 9 shown, this embodiment also provides a refrigeration pipe assembly, which is a manifold and includes the steel three-way connector 10 provided by this embodiment and three copper connecting pipe segments 20, 30, 40. The copper connecting pipe segment 20 is welded to one end of the main pipe 1 to form the collecting pipe 100 of the manifold, the copper connecting pipe segment 30 is welded to the other end of the main pipe 1 to form one branch pipe 200 of the manifold, and the copper connecting pipe segment 40 is welded to the connecting pipe 3 to form the other branch pipe 300 of the manifold. Among them, the extension length L1 of the collecting pipe 100 is greater than or equal to twice the outer diameter D at the middle region of the connecting pipe 3, and the extension length of at least one of the branch pipe 200 and the other branch pipe 300 is greater than four times the outer diameter D at the middle region of the connecting pipe 3. The extension length L1 of the collecting pipe 100 refers to the shortest vertical distance from the connection point of the plastic convex part 11 and the main pipe 1 to the end of the copper connecting pipe segment 20; the extension length L2 of the branch pipe 200 refers to the shortest vertical distance from the connection point of the plastic convex part 11 and the main pipe 1 to the end of the copper connecting pipe segment 30; the extension length L3 of the other branch pipe 300 refers to the vertical distance from the center of the end face of the insertion end of the connecting pipe 3 to the end of the copper connecting pipe segment 40.

[0113] Although this embodiment takes the refrigeration pipe assembly as a manifold as an example for illustration. However, the utility model does not make any limitation thereto. The steel three-way connector provided by this embodiment can also be combined with other components in the pipeline system to form other refrigeration pipe assemblies. In addition, although this embodiment takes the steel three-way connector applied to a refrigeration system with a high working pressure as an example. However, the utility model does not make any limitation thereto. In other embodiments, the steel three-way connector provided by the utility model is also applicable to other pipeline systems with a small working pressure, such as a low-pressure water pipeline system.

[0114] Embodiment Two

[0115] This embodiment is basically the same as Embodiment One and its variations, the difference being that: as Figure 10 andFigure 11 As shown, in the steel three-way connector 10 provided in this embodiment, the main pipe 1 has a single-end open structure, and two plastic convex portions 11, 11' extending respectively to both sides of the axis of the main pipe 1 are formed on the peripheral wall of the main pipe 1; the steel three-way connector includes two connectors 2, 2' and two connecting pipes 3, 3'.

[0116] Specifically, as Figures 11 to 12A shown, a welding plane 12 is formed at the end of the plastic convex portion 11, and a fluid through-hole 121 is opened on the welding plane 12. The connector 2 is welded to the welding plane 12, and a connecting pipe hole 21 whose axis axially intersects with the open end of the main pipe 1 at an obtuse angle α1 is opened thereon. The connecting pipe 3 is welded to the connecting pipe hole 21 on the connector 2. Similarly, a welding plane 12' is formed at the end of the plastic convex portion 11', and a fluid through-hole 121' is opened on the welding plane 12'. The connector 2' is welded to the welding plane 12', and a connecting pipe hole 21' whose axis axially intersects with the open end of the main pipe 1 at an obtuse angle α2 is opened thereon. The connecting pipe 3' is welded to the connecting pipe hole 21' on the connector 2'. The two connecting pipes 3, 3' and the open end of the main pipe 1 together form the three connecting pipe ends of the steel three-way connector.

[0117] In this embodiment, the axes of the two connecting pipe holes 21, 21' are symmetrically distributed on both sides of the axis of the main pipe 1 approximately, that is, the obtuse angles α1 and α2 are basically equal. However, the present utility model does not make any limitation in this regard. In other embodiments, the two connecting pipe holes can also be arranged asymmetrically. Compared with the first embodiment, the steel three-way connector provided in this embodiment is a three-way connector that diverges to both sides and has a structure approximately in the shape of a Y.

[0118] In this embodiment, as Figure 12 and Figure 13 shown, the main pipe 1 is formed by local bulging of a single-end open thin-walled tensile cylinder. However, the present utility model does not make any limitation in this regard. In other implementations, the main pipe can also include a thin-walled pipe body with both ends open and an end cap for blocking one of the open ends of the thin-walled pipe body, and two relatively distributed plastic convex portions are formed after local bulging of the thin-walled pipe body.

[0119] Basically the same as the first embodiment, in this embodiment, both of the two welding planes 12, 12' slightly extend past the corresponding main pipe highest generatrix K and main pipe highest generatrix K' on the main pipe 1; that is, neither of the two plastic convex portions 11, 11' has a plastic straight section, and the lowest points of the two welding planes in the extending direction are basically close to the corresponding main pipe highest generatrix, as Figure 13 shown. However, the present utility model does not make any limitation in this regard. In other embodiments, based on the allowability of the forming process and the wall thickness of the main pipe, the two plastic convex portions 11, 11' can also be provided with a certain plastic straight section, as Figure 14 shown.

[0120] In this embodiment, the closed end 14 of the main pipe 1 has a columnar structure. However, the present utility model does not make any limitation in this regard. In other embodiments, in order to further reduce the material cost of the main pipe 1, the closed end 14 of the main pipe 1 can also be set to have other structures such as a conical shape with a gradually decreasing cross-section, a frustum shape, or a depression towards the open end of the main pipe. Figure 15 The figure shows a schematic structural diagram of a steel three-way connector with the closed end 14 of the main pipe 1 being conical. Figure 15A As shown in Figure 15 the sectional schematic diagram of Figure 15B As shown in Figure 15 the schematic structural diagram of the main pipe 1 in . In this structure, except for the two welding planes 12, 12', the other outer peripheral wall regions of the main pipe 1 are still curved. However, the present utility model does not make any limitation in this regard.

[0121] In other embodiments, the outer peripheral wall region of the main pipe between the two welding planes can also be set to be an inclined plane; for example, Figure 16 , Figure 16A and Figure 16B As shown, four plastic protrusion parts extending respectively to both sides of the axis of the main pipe 1 are formed on the peripheral wall of the main pipe 1, and an inclined welding plane is formed at the end of each plastic protrusion part so that the closed end 14 of the main pipe 1 has a quadrangular pyramid structure. Fluid through holes 121, 121' are respectively opened on the two symmetrically distributed welding planes 12, 12'. Two connectors 2, 2' are respectively welded to the two welding planes 12, 12'; two connecting pipes 3, 3' are respectively welded and connected to the connecting pipe holes on the two connectors. In this structure, the main pipe 1 is first stretched by a cylinder to form a structure with a conical closed end and a cylindrical open end, as shown in Figure 16C ; then, metal plastic processing (such as hydroforming) is performed on the conical closed end to form the four plastic protrusion part structures shown in Figure 16A . Figure 17 The figure shows a schematic structural diagram of a steel three-way connector with the closed end 14 of the main pipe 1 being recessed towards the open end. Figure 17A As shown in Figure 17 the sectional schematic diagram of Figure 17B As shown in Figure 17 the schematic structural diagram of the main pipe 1 in . In this structure, a V-shaped groove 141 is formed at the closed end of the main pipe, and two inner side walls 142, 142' of the V-shaped groove 141 form two guiding surfaces to guide the fluid in the main pipe 1 into the two fluid through holes 121, 121'.

[0122] Regarding the welding plane 12, in other embodiments, the two welding planes 12, 12' can also be set to be substantially parallel to the axis of the main pipe 1. Specifically, Figure 18The following is an assembly schematic diagram of the main pipe 1 and the connecting piece 2 in the steel three-way connecting piece provided by another embodiment of the present utility model. In this structure, the two welding planes 12, 12' are substantially parallel to the axis of the main pipe 1 and are basically flush with the corresponding highest generatrix of the main pipe. The two connecting pieces 2, 2' are both circular connecting pipes, and the welding ends of the circular connecting pipes are in the shape of inclined planes to fit the corresponding welding planes. The pipe holes of the circular connecting pipes serve as the connecting pipe holes 21, 21'. In Figure 18 the main pipe 1 includes a thin-walled pipe body 1a with both ends open and an end cover 1b for plugging one open end of the thin-walled pipe body 1a. After local bulging of the thin-walled pipe body 1a, two relatively distributed plastic bulge portions 11, 11' are formed (as Figure 19 shown). Similarly, the present utility model does not make any limitation in this regard. In other embodiments, the main pipe may also be a single-ended open tensile cylinder body that forms plastic bulge portions after local bulging, such as Figure 20A , Figure 20B and Figure 20C shown. Compared with Figure 20A , Figure 20B in which four plastic bulge portions 11 protrude outward from the peripheral wall of the main pipe near the closed end 14, so that the inner diameter of the closed end 14 of the main pipe is greater than the inner diameter of the open end of the main pipe 1 to form a larger liquid separation cavity. Fluid through holes 121, 121' are respectively opened on the two symmetrically distributed welding planes 12, 12'. The two connecting pieces 2, 2' are respectively welded and fitted to the two welding planes 12, 12'; the two connecting pipes 3, 3' are respectively welded and connected to the connecting pipe holes on the two connecting pieces. In this structure, the two connecting pieces 2, 2' are circular connecting pipes with inclined plane welding ends 22, and the pipe holes of the circular connecting pipes serve as connecting pipe holes to be respectively welded and connected to the two connecting pipes 3, 3'. Figure 20C Shown in Figure 20B is the structural schematic diagram of the main pipe in Figure 20D Shown in Figure 20C is the cross-sectional schematic diagram of the main pipe shown in

[0123] In this embodiment, the welding plane 12 is the outer surface at the end of the plastic convex part, and the connecting member 2 includes a plurality of stacked sheet liners 2a. During welding, after the plurality of sheet liners 2a are integrally formed by self-fusion welding, the innermost sheet liner 2a is pre-fixed to the corresponding welding planes 12, 12' through a self-fusion weld; finally, the main pipe 1, the two connecting members 2, 2' and the two connecting pipes 3, 3' are integrally welded and formed by furnace brazing, and brazed welds for sealed connection are formed between the innermost sheet liner 2a and the corresponding welding planes 12, 12' and between adjacent sheet liners 2a. However, the present utility model does not make any limitation thereto. For other possible structures of the welding plane, other possible structures of the connecting member, the welding connection method between the connecting member and the welding plane, and the connection method of the connecting pipe, etc., this embodiment is basically the same as Embodiment 1 and its variations, and will not be elaborated herein.

[0124] Correspondingly, as Figure 21 shown, this embodiment further provides a refrigeration pipe assembly, which is a manifold and includes the steel three-way connecting member 10 provided in this embodiment and three copper pipe sections 20, 30, 40. The copper pipe section 20 is welded to the open end of the main pipe 1 to form the collecting pipe 100 of the manifold, the copper pipe section 30 is welded to the connecting pipe 3 to form one branch pipe 200 of the manifold, and the copper pipe section 40 is welded to the connecting pipe 3' to form the other branch pipe 300 of the manifold. Among them, the extension length L1 of the collecting pipe 100 is greater than or equal to twice the outer diameter D at the middle region of the connecting pipe 3, and the extension length of at least one of the branch pipe 200 and the other branch pipe 300 is greater than four times the outer diameter D at the middle region of the connecting pipe 3. The extension length L1 of the collecting pipe 100 refers to the shortest vertical distance from the connection point of the plastic convex part 11 and the main pipe 1 to the end of the copper pipe section 20; the extension length L2 of the branch pipe 200 refers to the vertical distance from the center of the end face of the insertion end of the connecting pipe 3 to the end of the copper pipe section 30; the extension length L3 of the other branch pipe 300 refers to the vertical distance from the center of the end face of the insertion end of the connecting pipe 3' to the end of the copper pipe section 40.

[0125] Figure 22 shown is a schematic structural diagram of a manifold formed by the steel three-way connecting member provided in another embodiment of the present utility model based on Figure 18 shown.

[0126] Although this embodiment is described by taking the refrigeration pipe assembly as a manifold as an example, the present invention makes no limitation thereto. The steel three-way connector provided in this embodiment can also form other refrigeration pipe assemblies after being combined with other components in the pipeline system. In addition, although this embodiment takes the steel three-way connector applied to a refrigeration system with a high working pressure as an example, the present invention also makes no limitation thereto. In other embodiments, the steel three-way connector provided by the present invention is also applicable to other pipeline systems with a relatively small working pressure, such as a low-pressure water pipeline system.

[0127] Embodiment 3

[0128] This embodiment is basically the same as Embodiment 1 and its variations, the difference being that: as Figure 23 , Figure 23A and Figure 24 shown, the structure of the steel three-way connector 10 provided in this embodiment is generally in a T shape, and the plastic convex part 11 vertically protrudes from the peripheral wall of the main pipe 1 to one side of the main pipe 1. The two ends of the main pipe 1 and the connecting pipe 3 together form the three connecting pipe ends of the steel three-way connector.

[0129] In this embodiment, as Figure 25 and Figure 25A shown, the welding plane 12 at the end of the plastic convex part 11 is substantially parallel to the axis of the main pipe 1 and the welding plane 12 is substantially flush with the highest generatrix K of the main pipe 1 in the extending direction of the plastic convex part 11. However, the present invention makes no limitation thereto. In other embodiments, based on the allowability of the forming process and the wall thickness of the main pipe, it is also possible to set the plastic convex part to have a certain plastic straight section so that the welding plane extends beyond the highest generatrix of the main pipe.

[0130] In this embodiment, the projection plane of the welding plane 12 in the extending direction of the plastic convex part 11 is square, and the fluid through hole 121 is a circular through hole, as Figure 25 shown. However, the present invention makes no limitation thereto. In other embodiments, it is also possible to set the projection plane of the welding plane 12 in the extending direction of the plastic convex part 11 to be elliptical (as Figure 26 shown) or other polygons.

[0131] Substantially the same as in the first embodiment, in this embodiment, the welding plane 12 is the outer surface at the end of the plastic protrusion, and the connecting member 2 includes multiple sheet-shaped liners 2a stacked in sequence. During welding, after the multiple sheet-shaped liners 2a are integrally formed by self-fusion welding, the innermost sheet-shaped liner 2a is pre-fixed to the corresponding welding plane 12 through a self-fusion weld; finally, the main pipe 1, the connecting member 2, and the connecting pipe 3 are integrally welded and formed by furnace brazing, and brazed welds for sealed connection are formed between the innermost sheet-shaped liner 2a and the welding plane 12 and between adjacent sheet-shaped liners. However, the present utility model does not make any limitation in this regard. For other possible structures of the welding plane, other possible structures of the connecting member, the welding connection method between the connecting member and the welding plane, and the connection method of the connecting pipe, etc., this embodiment is substantially the same as the first embodiment and its variations, and will not be elaborated here.

[0132] Figure 27 The figure shows a schematic structural diagram of a refrigeration pipe assembly provided by another embodiment of the present utility model. This refrigeration pipe assembly is a manifold pipe assembly, which includes a steel three-way connecting member 10 and multiple branch pipes 50. In this structure, the connection method between the main pipe 1 and the connecting pipe 3 is substantially the same as that of the T-shaped steel three-way connecting member in this embodiment, the difference being that: Figure 27 Both ends of the main pipe 1 are blocked. Multiple branch pipes 50 are welded to the other side of the main pipe 1 opposite to the connecting pipe 3. A plastic protrusion 11 is formed on the peripheral wall of the main pipe 1, and a welding plane 12 substantially parallel to the axis of the main pipe is formed at the end of the plastic protrusion 11. A connecting member 2 is welded and attached to the welding plane 12. The connecting pipe 3 is socket-welded in the connecting pipe hole on the connecting member 2; multiple branch pipes 50 with smaller diameters are welded in the branch pipe holes on the wall of the main pipe 1. However, the present utility model does not make any limitation in this regard. In other embodiments, two plastic protrusions may also be formed on the peripheral wall of the main pipe, and a welding plane is formed at the end of each plastic protrusion. A connecting member is welded and attached to each welding plane. A connecting pipe hole for socket-welding the connecting pipe is provided on one of the connecting members, and multiple branch pipe holes for welding connection of multiple branch pipes are provided on the other connecting member.

[0133] Figure 28 The figure shows a schematic structural diagram of a manifold pipe assembly provided by another embodiment of the present utility model. Compared with Figure 27 , Figure 28 the main pipe 1 in is shorter in length, one end of it is blocked, and the other end is connected to the end connecting pipe 60. Multiple branch pipes 50 are welded to the peripheral wall of the end connecting pipe 60. The shorter main pipe 1 will be more conducive to the formation of the plastic protrusion 11. The present utility model does not make any limitation on the welding positions of the multiple branch pipes 50. In other embodiments, multiple branch pipes may also be partially welded to the main pipe 1 and partially welded to the end connecting pipe 60.

[0134] Embodiment 4

[0135] This embodiment is basically the same as Embodiment 3 and other variations, except that: as Figure 29 shown, the main pipe 1 has a single-ended open structure, which includes a thin-walled pipe body 1a with both ends open and an end cap 1b for plugging one of the open ends of the thin-walled pipe body 1a. Two plastic convex portions 11, 11' that vertically protrude toward both sides of the axis of the main pipe 1 are formed on the peripheral wall of the main pipe 1. The steel three-way connector includes two connectors 2, 2' and two connecting pipes 3, 3'. Specifically, a welding plane 12 that is basically parallel to the axis of the main pipe 1 is formed at the end of the plastic convex portion 11, and the welding plane 12 is basically flush with the highest generatrix of the corresponding main pipe. The connector 2 is welded to the welding plane 12 and a connecting pipe hole whose axis is basically perpendicular to the open end axis of the main pipe 1 is formed thereon (the connecting pipe 3 has been assembled in the connecting pipe hole in the figure, so the label is not shown), and the connecting pipe 3 is welded to the connecting pipe hole on the connector 2. The plastic convex portion 11' is the same as the plastic convex portion 11, and is symmetrically distributed on the other side of the main pipe 1. The two connecting pipes 3, 3' and the open end of the main pipe 1 together form the three connecting pipe ends of the steel three-way connector 10.

[0136] In this embodiment, both of the two connecting pipes 3, 3' are straight pipes. However, the present utility model does not make any limitation thereto. In other embodiments, as Figure 30 shown, both of the two connecting pipes 3, 3' may also be bent pipes; or, one of the connecting pipes is a straight pipe and the other connecting pipe is a bent pipe.

[0137] Although this embodiment takes the example of plugging one of the open ends of the thin-walled pipe body with an end cap to illustrate the structure of the main pipe. However, the present utility model does not make any limitation thereto. In other embodiments, the main pipe may also be a single-ended open drawn cylinder, and two plastic convex portions that vertically protrude toward both sides of the main pipe are formed after local bulging of the drawn cylinder, or four plastic convex portions are formed so that the cross-section of the main pipe at that place is square. For details, reference can be made to Figure 20A and Figure 20C shown.

[0138] Basically the same as Embodiment 3, in this embodiment, the welding plane 12 is the outer surface at the end of the plastic convex portion 11, and the connector 2 includes a plurality of sheet-shaped lining plates 2a stacked in sequence. However, the present utility model does not make any limitation thereto. For other possible structures of the welding plane, other possible structures of the connector, the welding connection method between the connector and the welding plane, and the connection method of the connecting pipe, etc., this embodiment is basically the same as Embodiment 1 and its variations, and will not be elaborated here.

[0139] Correspondingly, this embodiment also provides a refrigeration pipe assembly, which includes the above-mentioned steel three-way connecting pipe and three copper pipe sections. One of the copper pipe sections is connected to the open end of the main pipe, and the other two copper pipe sections are respectively connected to the two connecting pipes. The arrangement of the three copper pipe sections enables the steel three-way connector provided in this embodiment to be welded and connected to the copper pipe in the existing refrigeration system by flame brazing.

[0140] Embodiment Five

[0141] This embodiment is basically the same as Embodiment One and its variations, except that: as Figures 31 to 34 shown, in this embodiment, the main pipe 1 is a bent pipe with open ends at both ends, and the two ends of the main pipe 1 face different directions.

[0142] Specifically, the plastic convex portion 11 protrudes and extends outward from the bending portion of the main pipe 1, and the welding plane 12 at the end of the plastic convex portion 11 is inclined relative to the axis of the bending portion of the main pipe 1. Specifically, it is manifested as the welding plane intersecting with the tangent of the axis of the bending portion of the main pipe 1. The welding plane 12 is basically flush with the highest generatrix K of the main pipe 1 in the extending direction of the plastic convex portion 11, as Figure 33 shown. However, the present invention does not make any limitation in this regard. In other embodiments, the welding plane may also be basically parallel to the axis of the bending portion of the main pipe (i.e., parallel to the tangent of the axis of the bending portion), and it may also extend beyond the highest generatrix K of the main pipe. The two ends of the main pipe 1 and the connecting pipe 3 together form the three connecting pipe ends of the steel three-way connector 10, so that the steel three-way connector provided in this embodiment is generally in a Y-shaped structure.

[0143] In this embodiment, the welding plane 12 is the outer surface at the end of the plastic convex portion 11, and its projection surface in the extending direction of the plastic convex portion 11 is circular. The connector 2 also includes a plurality of sheet-shaped liners 2a that are stacked and welded to the welding plane 12 in sequence, and each sheet-shaped liner 2a is an annular liner. However, the present invention does not make any limitation in this regard. For other possible structures of the welding plane, other possible structures of the connector, the welding connection method between the connector and the welding plane, and the connection method of the connecting pipe, etc., this embodiment is basically the same as Embodiment One and its variations, and will not be elaborated here.

[0144] Correspondingly, this embodiment also provides a refrigeration pipe assembly. As Figure 35As shown, the refrigeration pipe assembly is a manifold, which includes the steel three-way connector 10 provided in this embodiment, and three copper pipe segments 20, 30, 40. The copper pipe segment 20 is welded to one end of the main pipe 1 to form the collecting pipe 100 of the manifold. The copper pipe segment 30 is welded to the connecting pipe 3 to form one branch pipe 200 of the manifold. The copper pipe segment 40 is welded to the other end of the main pipe 1 through the transition section 70 to form the other branch pipe 300 of the manifold. However, the present utility model does not make any limitation thereto. In other embodiments, the copper pipe segment 40 may also be directly connected to the other end of the main pipe 1 to form the other branch pipe 300 of the manifold.

[0145] In this embodiment, the extension length L1 of the collecting pipe 100 is greater than or equal to twice the outer diameter D of the middle region of the connecting pipe 3, and the extension length of at least one of the branch pipe 200 and the other branch pipe 300 is greater than four times the outer diameter D of the middle region of the connecting pipe 3. The extension length L1 of the collecting pipe 100 refers to the shortest vertical distance from the connection between the plastic protrusion 11 and the main pipe 1 to the end of the copper pipe segment 20. The extension length L2 of the branch pipe 200 refers to the vertical distance from the center of the end face of the insertion end of the connecting pipe 3 to the end of the copper pipe segment 30. The extension length L3 of the other branch pipe 300 refers to the shortest vertical distance from the connection between the plastic protrusion 11 and the main pipe 1 to the end of the copper pipe segment 40.

[0146] Although this embodiment is described by taking the refrigeration pipe assembly as a manifold as an example. However, the present utility model does not make any limitation thereto. The steel three-way connector provided in this embodiment can also be combined with other components in the pipeline system to form other refrigeration pipe assemblies.

[0147] In addition, although this embodiment takes the steel three-way connector applied to a refrigeration system with a high working pressure as an example. However, the present utility model also does not make any limitation thereto. In other embodiments, the steel three-way connector provided by the present utility model is also applicable to other pipeline systems with a small working pressure, such as a low-pressure water pipeline system.

[0148] Embodiment Six

[0149] This embodiment is basically the same as Embodiment Five and its variations, the difference being that: as Figure 36 shown, in this embodiment, the orientations of the two ends of the bent main pipe 1 are substantially the same, and the steel three-way connector formed by the two ends of the main pipe 1 and the connecting pipe 3 is generally in a U-shaped structure.

[0150] Specifically, as Figure 36A and Figure 37AAs shown, the plastic protrusion 11 protrudes outward from the bent portion of the main pipe 1 and extends in a direction substantially parallel to the extending direction of the end of the main pipe 1. The welding plane 12 at the end of the plastic protrusion 11 is substantially parallel to the axis of the bent portion of the main pipe 1, specifically, the welding plane 12 is substantially parallel to the tangent of the axis of the bent portion of the main pipe 1, and the welding plane 12 is substantially flush with or slightly extends beyond the highest generatrix K of the main pipe 1 in the extending direction of the plastic protrusion 11. The axis of the connection hole 21 is substantially parallel to the extending direction of the end of the main pipe 1 and the connecting pipe 3 is a straight pipe. However, the present utility model does not make any limitation thereto. In other embodiments, the extending direction of the plastic protrusion 11 may also be perpendicular to the plane where the axis of the main pipe 1 is located, and the connecting pipe 3 may also be a bent pipe so that the steel three-way connector has a claw-shaped structure, such as Figure 38 and Figure 38A shown.

[0151] In this embodiment, the welding plane 12 is the outer surface at the end of the plastic protrusion 11 and its projection plane in the extending direction of the plastic protrusion 11 is circular. The connector 2 also includes a plurality of sheet-shaped liners 2a that are stacked in sequence and welded to the welding plane 12, and each sheet-shaped liner 2a is an annular liner. However, the present utility model does not make any limitation thereto. For other possible structures of the welding plane, other possible structures of the connector, the welding connection manner between the connector and the welding plane, and the connection manner of the connecting pipe, etc., this embodiment is basically the same as Embodiment 1 and its variations, and will not be elaborated herein.

[0152] Basically the same as Embodiment 1, in this embodiment, the cross-sectional area of the plastic protrusion 11 gradually increases along its extending direction (as Figure 37B shown), and the area of the region surrounded by the outer contour line of the welding plane 12 is larger than the inner hole cross-sectional area of the non-plastic protrusion region 13 on the main pipe 1. This setting enables the welding plane 12 to provide a larger bearing area for the connector 2. While the aperture of the connection hole 21 is close to the inner hole aperture of the non-plastic protrusion region 13 on the main pipe 1, it ensures that there is a fitting area that meets the welding strength between the connector 2 and the welding plane 12, thereby enabling the steel three-way connector provided in this embodiment to be an equal-diameter three-way or a near-equal-diameter three-way; or alternatively, the aperture of the connection hole is larger than the inner hole aperture of the non-plastic protrusion region on the main pipe. However, the present utility model does not make any limitation thereto.

[0153] Figure 39The following is a schematic structural diagram of a steel three-way connector provided by another embodiment of the present utility model. The difference from this embodiment is that: the fluid through-hole 121 formed on the welding plane 12 is a flanged hole. The flanged portion 1211 of the fluid through-hole 121 is inserted into the front end of the connecting pipe 3 and is brazed to the inner peripheral wall of the front end of the connecting pipe 3, while the outer peripheral wall of the front end of the connecting pipe 3 is brazed to the inside of the connecting pipe hole 21 on the connector 2. This setting increases the brazing surface of the connecting pipe 3 to further improve the connection strength and pressure resistance after brazing. However, the present utility model does not make any limitation on the flanging height of the fluid through-hole 121, and the brazing depth of the connecting pipe 3 is still mainly provided by the connecting pipe hole 21 on the connector 2.

[0154] Correspondingly, this embodiment also provides a refrigeration pipe assembly. As Figure 40 shown, this refrigeration pipe assembly is a manifold, which includes the steel three-way connector 10 provided by this embodiment and three copper connecting pipe segments 20, 30, 40. The copper connecting pipe segment 20 is welded to the connecting pipe 3 to form the collecting pipe 100 of the manifold. The copper connecting pipe segment 30 is welded to one end of the main pipe 1 to form one branch pipe 200 of the manifold. The copper connecting pipe segment 40 is welded to the other end of the main pipe 1 to form the other branch pipe 300 of the manifold. Among them, the extension length L1 of the collecting pipe 100 is greater than or equal to twice the outer diameter D at the middle region of the connecting pipe 3. At least one of the extension lengths of the branch pipe 200 and the other branch pipe 300 is greater than four times the outer diameter D at the middle region of the connecting pipe 3. The extension length L1 of the collecting pipe 100 refers to the vertical distance from the welding plane 12 to the end of the copper connecting pipe segment 20. The extension length L2 of the branch pipe 200 refers to the vertical distance from the welding plane 12 to the end of the copper connecting pipe segment 30. The extension length L3 of the other branch pipe 300 refers to the vertical distance from the welding plane 12 to the end of the copper connecting pipe segment 40.

[0155] Although this embodiment is described by taking the refrigeration pipe assembly as a manifold as an example. However, the present utility model does not make any limitation on this. The steel three-way connector provided by this embodiment can also be combined with other components in the pipeline system to form other refrigeration pipe assemblies. In addition, although this embodiment takes the steel three-way connector applied to a refrigeration system with a high working pressure as an example. However, the present utility model also does not make any limitation on this. In other embodiments, the steel three-way connector provided by the present utility model is also applicable to other pipeline systems with a smaller working pressure, such as a low-pressure water pipeline system.

[0156] Embodiment Seven

[0157] This embodiment provides another structure of a steel three-way connector. Specifically, as Figure 41 and Figure 42As shown in the figure, the steel three-way connector includes a steel main pipe 1, a connector 2, and two connecting pipes 3. The main pipe 1 is a thin-walled circular pipe fitting with an open end at one end. On the peripheral wall of the main pipe 1, there is a plastic convex part 11 extending outward from the main pipe through metal plastic forming. The outer wall 111 of the plastic convex part 11 near the closed end 14 of the main pipe is basically flush with the outer end wall of the closed end 14 of the main pipe and forms a welding plane 12 together with the outer end wall of the closed end 14 of the main pipe. Two fluid through holes 121 are provided on the welding plane 12. The connector 2 is welded to the welding plane 12, and two connecting pipe holes (the connecting pipe holes are assembled with connecting pipes, so they are not numbered) respectively communicating with the two fluid through holes 121 are provided on the connector 2. The two connecting pipes 3 are both thin-walled circular pipe fittings, and the two connecting pipes 3 are respectively sleeved and welded to the two connecting pipe holes on the connector 2 and / or the fluid through holes 121 on the corresponding welding plane; the open end of the main pipe 1 and the two connecting pipes 3 together form the three interface ends of the steel three-way connector.

[0158] In practical applications, in order to extend the assembly length of the steel three-way connector, a main pipe connecting pipe 4 can also be welded to the open end of the main pipe 1, as Figure 41 shown. However, the present utility model makes no limitation thereto. In other embodiments, the external connecting pipe can also be directly connected to the open end of the main pipe.

[0159] In this embodiment, the peripheral walls on both sides of the main pipe 1 near the closed end bulge radially to form plastic convex parts 11, and the outer walls 111 of the two plastic convex parts near the closed end 14 of the main pipe are both basically flush with the outer end part of the closed end 14 of the main pipe. However, the present utility model makes no limitation thereto. In other embodiments, the main pipe can also have only one side bulge radially to form a plastic convex part.

[0160] In this embodiment, the welding plane 12 is elliptical, and the two fluid through holes 121 are arranged along the long radius direction of the ellipse so that the closed end of the main pipe 1 is flat, thereby reducing the volume of the steel three-way connector. However, the present utility model makes no limitation thereto. In other embodiments, the welding plane can also be polygonal, such as a rectangle or a pentagon with rounded corners, etc.; similarly, the width of the welding plane in the arrangement direction of the two fluid through holes is greater than the width in another direction perpendicular to the arrangement direction.

[0161] In this embodiment, the connector 2 includes one or more integrally stacked steel integral sheet liners that are welded to the welding plane 12. Two liner holes 2a1 are provided on the integral sheet liner 2a to form connecting pipe holes. However, the present utility model makes no limitation thereto. In other embodiments, the two connecting pipe holes can be respectively arranged on independent connectors; for example, two independent sheet liners are welded to the welding plane, and a liner hole is correspondingly provided on each sheet liner to form a connecting pipe hole. As Figure 43As shown, the integral sheet liner 2a is oval. However, the present utility model is not limited thereto; in other embodiments, the sheet liner may also be circular or other polygons. For the welding method of the sheet liner, this embodiment is basically the same as that of Embodiment 1 and its variations. First, a self-fusion weld can be used for pre-fixation and then furnace brazing can be carried out. The integral sheet liner is hermetically connected to the welding plane 12 through the brazing weld. Although this example details the connector 2 with the sheet liner as an example. However, the present utility model makes no limitation thereto. Basically the same as that of Embodiment 1 and its variations, the connector may also be a circular connecting pipe or a flanged seat.

[0162] Correspondingly, this embodiment also provides a refrigeration pipe assembly, which includes the steel three-way connecting pipe provided in this embodiment and three copper pipe sections. One of the copper pipe sections is connected to the open end of the main pipe, and the other two copper pipe sections are respectively connected to the two connecting pipes. The setting of the three copper pipe sections enables the steel three-way connector provided in this embodiment to be welded and connected to the copper pipeline of the existing refrigeration system by flame brazing.

[0163] In summary, in the steel three-way connector provided by the present utility model, a plastic protrusion extending outward from the main pipe is formed on the thin-walled circular main pipe by metal plastic forming. The end of the plastic protrusion forms a welding plane to realize the fitting welding of the connector. The connecting pipe is socket-connected to the connecting pipe hole on the connector and / or the fluid through hole on the welding plane. In the present utility model, the plastic protrusion does not provide the welding depth for the connecting pipe. It is only used to form a welding plane for the surface welding connection of the connector. Therefore, the deformation amount of the plastic protrusion only needs to satisfy that the welding plane is basically flush with or extends beyond the highest generatrix of the main pipe in the extending direction of the plastic protrusion; this setting greatly reduces the difficulty of metal plastic processing of the steel main pipe and also effectively reduces the processing energy consumption. Further, in the steel three-way connector provided by the present utility model, the connecting pipe hole is no longer directly formed on the large-volume main pipe, but on the relatively small-volume connector. Based on this setting, only by controlling the hole depth of the connecting pipe hole on the connector can the surface brazing connection of the connecting pipe be realized, and thus the connection strength and pressure resistance after welding of the connecting pipe can both meet the requirements of the refrigeration system; while the relatively large-volume main pipe can use thin-walled pipe fittings to greatly reduce the material cost of the steel three-way connector, and the thin-walled main pipe is also more conducive to the forming of the plastic protrusion.

[0164] Although the present utility model has been disclosed above with the preferred embodiments, it is not intended to limit the present utility model. Any person skilled in this art can make some modifications and refinements without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the scope required by the claims.

Claims

1. A steel three-way connector, characterized in that: Including steel main pipes, connectors and nozzles; The main pipe is a thin-walled circular pipe. A plastic protrusion extending to the outside of the main pipe is formed on the peripheral wall of the main pipe by metal plastic molding. A welding plane substantially parallel to the main pipe axis or inclined relative to the main pipe axis is formed at the end of the plastic protrusion. The welding plane is substantially flush with or extends over the highest generatrix of the main pipe in the extension direction of the plastic protrusion. A fluid through hole is opened on the welding plane. A connecting piece is welded to the welding plane and is provided with a connecting hole connected to the fluid through hole; The connecting pipe is a thin-walled circular pipe, and the connecting pipe is sleeve-welded to the connecting pipe hole on the connecting piece and / or the fluid through hole on the welding plane.

2. The steel three-way connector according to claim 1, characterized in that: The cross-sectional area of ​​the plastic protrusion gradually increases along its extension direction, and the area of ​​the region enclosed by the outer contour line of the welding plane is greater than or equal to the cross-sectional area of ​​the inner hole of the non-plastic protrusion region on the main pipe.

3. The steel three-way connector according to claim 1, characterized in that: The projection surface of the welding plane in the extension direction of the plastic protrusion is any one of a circle, an ellipse or a polygon.

4. The steel three-way connector according to claim 1, characterized in that: The welding plane includes the outer surface and / or the inner surface of the end of the plastic protrusion, and the connecting piece includes one or more combinations of a circular connecting tube, a sheet lining plate or a flange seat.

5. The steel three-way connector according to claim 4, characterized in that: The connecting piece comprises a sheet-like lining plate or a plurality of sheet-like lining plates stacked in sequence and welded on a welding plane, wherein the sheet-like lining plate is a polygonal lining plate or an annular lining plate having a circular pipe hole.

6. The steel three-way connector according to claim 4, characterized in that: The flanging seat includes a flanging table and a flanging part. The flanging part is arranged around the outer edge of the connecting pipe hole and connected to the flanging table. The flanging table is welded to the welding plane formed by the outer surface of the end of the plastic protrusion or to the sheet lining. The connecting pipe is sleeve-welded to the flanging part.

7. The steel three-way connector according to claim 1, characterized in that: A self-fluxing weld and / or a brazing weld for fixing the connecting piece is formed between the connecting piece and the welding plane. The self-fluxing weld is a local weld or an integral circumferential weld.

8. The steel three-way connector according to claim 1, characterized in that: The main pipe is a straight pipe with two open ends. The plastic protrusion starts from the peripheral wall of the main pipe and tilts or vertically protrudes toward one side of the main pipe. The two ends of the main pipe and the pipe together form three pipe ends of the steel three-way connector.

9. The steel three-way connector according to claim 1, characterized in that: The main pipe is a bent pipe with two open ends and the two ends of the bent pipe face in different directions. The plastic protrusion protrudes outward from the bend of the main pipe, and the welding plane at the end of the plastic protrusion is substantially parallel to the axis of the bend of the main pipe or is inclined relative to the axis of the bend of the main pipe. The two ends of the main pipe and the pipe together constitute three pipe ends of the steel tee connector. Alternatively, the main pipe is a bent pipe with open ends and the two ends of the bent pipe are oriented in substantially the same direction, the plastic protrusion protrudes outward from the bend of the main pipe, the welding plane at the end of the plastic protrusion is substantially parallel to the axis of the bend of the main pipe, and the two ends of the main pipe and the pipe together constitute three pipe ends of the steel tee connector.

10. The steel three-way connector according to claim 1, characterized in that: The main pipe is a single-end open structure, and at least two plastic protrusions are formed on the peripheral wall of the main pipe, which protrude toward both sides of the main pipe axis respectively. A welding plane is formed at the end of each plastic protrusion, and a fluid through hole is opened on each welding plane. Two connecting pieces are respectively welded to two of the welding planes, and each connecting piece is provided with a pipe hole whose axis intersects the axial direction of the open end of the main pipe at a nearly right angle or obtuse angle. The two pipes connected to the two pipe holes and the open end of the main pipe together constitute the three pipe ends of the steel three-way connecting piece.

11. The steel three-way connector according to claim 10, characterized in that: The main pipe is a stretching cylinder with one end open; or the main pipe includes a thin-walled pipe with two ends open and an end cover for sealing one open end of the thin-walled pipe.

12. A steel three-way connector, characterized in that: It includes a steel main pipe, a connecting piece and two connecting pipes; The main pipe is a thin-walled circular pipe with a single open end. A plastic protrusion extending toward the outside of the main pipe is formed on the peripheral wall of the main pipe by metal plastic molding. The outer wall of the plastic protrusion near the closed end of the main pipe is substantially flush with the outer end wall of the closed end of the main pipe and forms a welding plane with the outer end wall of the closed end of the main pipe. Two fluid through holes are provided on the welding plane. A connecting piece is welded to the welding plane and is provided with two connecting pipe holes respectively connected to the two fluid through holes; The two connecting pipes are thin-walled circular pipes, and the two connecting pipes are respectively sleeved and welded to two connecting pipe holes on the connecting piece and / or the fluid through holes on the corresponding welding plane.

13. The steel three-way connector according to claim 12, characterized in that: The welding plane is elliptical or polygonal, and the width of the welding plane in the arrangement direction of the two fluid through holes is greater than the width in another direction perpendicular to the arrangement direction.

14. A refrigeration pipe assembly, characterized in that: A steel three-way connector comprising any one of claims 1 to 13.

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