A centering and spacing connecting pipe fitting for connecting inner and outer pipes of a coaxial heat exchanger

Abstract

The utility model relates to coaxial heat exchanger connecting pipe fitting technical field, and disclose a coaxial heat exchanger inner and outer pipe connecting centering and spacing connecting pipe fitting, including inner tube and outer tube, the end of inner tube is sealed through inner connecting sleeve pipe, the end of outer tube is sealed through outer connecting sleeve pipe, the inner wall of inner connecting sleeve pipe one end is provided with internal thread, the inside of inner connecting sleeve pipe other end is provided with inner stepped hole, the inside of outer connecting sleeve pipe one end is provided with external thread, the inside of outer connecting sleeve pipe other end is provided with outer stepped hole, the outside fixed connection of inner connecting sleeve pipe has the locating block, this coaxial heat exchanger inner and outer pipe connecting centering and spacing connecting pipe fitting, through the operation of split welding, the welding of two pipe fittings is independent, only need to control one pipeline and one connecting sleeve positioning each time, need not synchronous adjustment inner tube, outer tube and the relative position of connecting structure, operation is simpler, need not to use special fixture to keep the concentricity of each component.

Description

Technical Field

[0001] This utility model relates to the technical field of coaxial heat exchanger connecting pipe fittings, specifically a centering and gap-fixing connecting pipe fitting for connecting the inner and outer pipes of a coaxial heat exchanger. Background Technology

[0002] A coaxial heat exchanger consists of an inner tube and an outer tube. Hot and cold fluids flow in the inner tube and the annular gap between the inner and outer tubes, respectively, for heat transfer. Coaxial heat exchangers offer advantages such as pressure resistance, shock resistance, resistance to deformation, resistance to clogging, and smooth oil return. In traditional heat exchangers, a sleeve is commonly used to seal the inner and outer tubes, with the front and rear ends of the sleeve welded to the inner and outer tubes using brazing or arc welding.

[0003] According to Chinese Patent Publication No. CN217275734U, a coaxial heat exchanger end-sealing structure is disclosed. This device includes an inner tube and an outer tube, with the inner tube coaxially fitted inside the outer tube. The end of the inner tube extends beyond the end of the outer tube. The ends of the outer tube and the inner tube are sealed together by a connecting sleeve. An outer mounting tube and an inner mounting tube extend outwards from the front and rear ends of the connecting sleeve, respectively. The outer tube extends into the outer mounting tube and is welded to it. The inner tube passes through and protrudes from the inner mounting tube and is welded to it. The outer mounting tube and the inner mounting tube each have an outer stepped hole and an inner stepped hole, respectively, which are welded to the outer tube and the inner tube to form a single unit. The beneficial effects of this invention are: the outer stepped hole and the inner stepped hole allow the solder to penetrate evenly between the connecting sleeve and the outer tube, preventing solder accumulation. The welding heat is distributed evenly, avoiding burn-through due to localized overheating.

[0004] However, when using the above-mentioned existing technology, the outer tube needs to be inserted into the outer mating hole and the outer stepped hole at the same time, and the inner tube needs to pass through the inner mounting tube and protrude for welding. Special fixtures are required to ensure that the inner and outer tubes are concentric with the sleeve. Otherwise, it is easy to cause welding deviation, which is quite inconvenient. Therefore, we propose a centering and gap-fixed connection fitting for connecting the inner and outer tubes of a coaxial heat exchanger to solve the problems in the background. Utility Model Content

[0005] This utility model provides a centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger. It can solve the problem that in the prior art, the outer tube needs to be inserted into the outer mating hole and the outer stepped hole at the same time, and the inner tube needs to pass through the inner mounting tube and protrude for welding. Special clamps are required to ensure that the inner and outer tubes are concentric with the sleeve, otherwise it is easy to cause welding deviation, which is quite inconvenient.

[0006] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a centering and gap-fixing connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger, comprising an inner tube and an outer tube, wherein the end of the inner tube is sealed by an inner connecting sleeve, and the end of the outer tube is sealed by an outer connecting sleeve, wherein the inner wall of one end of the inner connecting sleeve is provided with an internal thread, and the inner side of the other end of the inner connecting sleeve is provided with an internal stepped hole, wherein the inner side of one end of the outer connecting sleeve is provided with an external thread, and the inner side of the other end of the outer connecting sleeve is provided with an external stepped hole, and a positioning block is fixedly connected to the outside of the inner connecting sleeve.

[0007] Preferably, one end of both the inner connecting sleeve and the outer connecting sleeve is provided with a guide bevel.

[0008] Preferably, one end of the positioning block is tapered.

[0009] Preferably, the outer connecting sleeve is convex.

[0010] Preferably, one end of the inner connecting sleeve has a groove that matches the protrusion of the outer connecting sleeve.

[0011] Preferably, spiral guide grooves are provided on the inner sides of both the inner and outer stepped holes.

[0012] Preferably, the external thread and the internal thread are configured as trapezoidal threads.

[0013] Preferably, the diameter of the inner stepped hole is larger than the outer wall diameter of the inner tube.

[0014] Preferably, the diameter of the outer stepped hole is larger than the outer wall diameter of the outer tube.

[0015] Preferably, the contact surface between the positioning block and the outer connecting sleeve is provided with an annular welding groove, the cross-sectional shape of which is adapted to the conical end of the positioning block, for accommodating the solder and forming a surrounding sealed welding structure.

[0016] Compared with the prior art, the beneficial effects achieved by this utility model are:

[0017] This invention involves placing an inner connecting sleeve over the outer wall of an inner tube, ensuring the inner wall of the inner sleeve fits snugly against the surface of the inner tube. A guide angle allows solder to enter the stepped inner hole of the inner connecting sleeve through this angle. A spiral guide groove allows the solder to flow around and fill the groove, spreading evenly to both sides after filling the groove, thus achieving a more uniform solder distribution and welding the inner connecting sleeve to the inner tube. Then, an outer connecting sleeve is placed over the outer wall of the outer tube, ensuring the inner wall of the outer connecting sleeve fits snugly against the outer wall of the outer tube. The above steps are repeated to weld the outer connecting sleeve to the outer tube, completing the separate welding operation. The welding of the two pipes is independent; only the positioning of one pipe and one connecting sleeve needs to be controlled each time, without the need for synchronous adjustments. The relative positions of the inner tube, outer tube, and connecting structure simplify the operation, eliminating the need for special clamps to maintain the concentricity of each component. The outer connecting sleeve's protrusion is then rotated into the inner connecting sleeve's groove. Because both the protrusion and groove have external threads, the outer and inner connecting sleeves are threaded together. The guiding nature of the thread profile automatically corrects concentricity deviations during thread engagement, ensuring the inner and outer tubes remain coaxial until the positioning block outside the inner connecting sleeve contacts the surface of the outer connecting sleeve. The tapered shape of one end of the positioning block allows solder to encircle the tapered groove, welding the positioning block to the outer connecting sleeve. This connects the outer and inner connecting sleeves, completing the installation of the connecting pipe fitting. Attached Figure Description

[0018] Figure 1 This is a perspective view of the entire utility model;

[0019] Figure 2 This is a perspective view of the inner and outer connecting sleeves of this utility model.

[0020] Figure 3 This is a cross-sectional view of the present invention;

[0021] Figure 4 This is an enlarged view of section A of this utility model.

[0022] Among them: 1. Inner tube; 2. Outer tube; 3. Inner connecting sleeve; 4. Outer connecting sleeve; 31. Internal thread; 32. Inner stepped hole; 33. Positioning block; 41. External thread; 42. External stepped hole. Detailed Implementation

[0023] The specific embodiments of this utility model are described in detail below, but it should be understood that the protection scope of this utility model is not limited to the specific embodiments.

[0024] Please see Figure 1-4 This utility model provides a technical solution:

[0025] A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger includes an inner tube 1 and an outer tube 2. The end of the inner tube 1 is sealed by an inner connecting sleeve 3, and the end of the outer tube 2 is sealed by an outer connecting sleeve 4. The inner wall of one end of the inner connecting sleeve 3 is provided with an internal thread 31, and the inner side of the other end of the inner connecting sleeve 3 is provided with an inner stepped hole 32. The inner side of one end of the outer connecting sleeve 4 is provided with an external thread 41, and the inner side of the other end of the outer connecting sleeve 4 is provided with an outer stepped hole 42. A positioning block 33 is fixedly connected to the outside of the inner connecting sleeve 3.

[0026] The above technical solution involves first fitting the inner connecting sleeve 3 onto the outside of the inner tube 1, ensuring the inner wall of the inner connecting sleeve 3 is flush with the surface of the inner tube 1. Then, a guide angle is used to allow the solder to enter the inner stepped hole 32 within the inner connecting sleeve 3. A spiral guide groove is created to allow the solder to flow around and fill the groove, eventually spreading evenly to both sides after filling the groove, thus achieving a more uniform solder distribution and welding the inner connecting sleeve 3 to the inner tube 1. Next, the outer connecting sleeve 4 is fitted onto the outer wall of the outer tube 2, ensuring the inner wall of the outer connecting sleeve 4 is flush with the outer wall of the outer tube 2. The above steps are repeated to weld the outer connecting sleeve 4 to the outer tube 2, completing the separate welding operation. The welding of the two pipes is independent; only the positioning of one pipe and one connecting sleeve needs to be controlled each time, without the need for simultaneous adjustment of the inner tube. 1. The relative positions of the outer tube 2 and the connecting structure make the operation simpler, eliminating the need for special clamps to maintain the concentricity of each component. Then, by rotating the protrusion of the outer connecting sleeve 4 into the groove of the inner connecting sleeve 3, and since the protrusion has an external thread 41 and the groove has an internal thread 31, the outer connecting sleeve 4 and the inner connecting sleeve 3 are threaded together. Due to the guiding nature of the thread profile, the concentricity deviation can be automatically corrected during the thread engagement process, so that the inner tube 1 and the outer tube 2 are ultimately kept coaxial until the positioning block 33 outside the inner connecting sleeve 3 contacts the surface of the outer connecting sleeve 4. Since one end of the positioning block 33 is tapered, the solder can surround the tapered groove of the positioning block 33 to weld the positioning block 33 and the outer connecting sleeve 4 together, thereby connecting the outer connecting sleeve 4 and the inner connecting sleeve 3 and completing the installation of the connecting pipe fitting.

[0027] Specifically, both the inner connecting sleeve 3 and the outer connecting sleeve 4 have guide bevels at one end.

[0028] Through the above technical solution, the guide angle can naturally guide the solder during welding, so that the molten solder can smoothly flow into the welding area of ​​the inner stepped hole 32 and the outer stepped hole 42 along the angle.

[0029] Specifically, one end of the positioning block 33 is tapered.

[0030] Through the above technical solution, the conical surface can form a surrounding solder receiving space, guide the solder to be evenly distributed along the conical surface, and improve the connection strength and sealing of the welding part between the positioning block 33 and the outer connecting sleeve 4.

[0031] Specifically, the outer connecting sleeve 4 is designed to be convex.

[0032] Through the above technical solution, the convex structure can form a complementary fit with the groove of the inner connecting sleeve 3.

[0033] Specifically, one end of the inner connecting sleeve 3 has a groove that matches the protrusion of the outer connecting sleeve 4.

[0034] Through the above technical solution, the matching concave and convex structure can realize the pre-positioning of the connector, ensuring that the initial positions of the two are aligned before the threads are screwed on.

[0035] Specifically, spiral guide grooves are provided on the inner sides of both the inner stepped hole 32 and the outer stepped hole 42.

[0036] Through the above technical solution, the spiral guide groove can guide the solder to fill the gap between the outer step hole 42 and the inner step hole 32 evenly along the spiral path, avoiding the solder from concentrating in a certain area due to gravity or surface tension, forming local accumulation or voids.

[0037] Specifically, the external thread 41 and the internal thread 31 are set as trapezoidal threads.

[0038] Through the above technical solutions, trapezoidal threads have the characteristics of high tooth profile strength and strong load-bearing capacity. They can also more smoothly correct concentricity deviations during the screwing process, and have small thread clearance, resulting in better sealing performance after connection.

[0039] Specifically, the diameter of the inner stepped hole 32 is larger than the outer wall diameter of the inner tube 1.

[0040] Through the above technical solution, the aperture difference formation can provide sufficient filling space for the solder.

[0041] Specifically, the diameter of the outer stepped hole 42 is larger than the outer wall diameter of the outer tube 2.

[0042] Through the above technical solution, the aperture difference formation can provide sufficient filling space for the solder, ensuring that the solder is fully filled and forms a strong bond.

[0043] Specifically, the contact surface between the positioning block 33 and the outer connecting sleeve 4 is provided with an annular welding groove. The cross-sectional shape of the annular welding groove is adapted to the conical end of the positioning block 33 to accommodate the solder and form a surrounding sealed welding structure.

[0044] The above-disclosed embodiments are only a few specific examples of the present utility model. However, the embodiments of the present utility model are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present utility model.

Claims

1. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger, comprising an inner tube (1) and an outer tube (2), characterized in that: The end of the inner tube (1) is sealed by the inner connecting sleeve (3), and the end of the outer tube (2) is sealed by the outer connecting sleeve (4). The inner wall of one end of the inner connecting sleeve (3) is provided with an internal thread (31), and the inner side of the other end of the inner connecting sleeve (3) is provided with an inner stepped hole (32). The inner side of one end of the outer connecting sleeve (4) is provided with an external thread (41), and the inner side of the other end of the outer connecting sleeve (4) is provided with an external stepped hole (42). The positioning block (33) is fixedly connected to the outside of the inner connecting sleeve (3).

2. The centering and gap-fixing connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: Both the inner connecting sleeve (3) and the outer connecting sleeve (4) have a guide bevel at one end.

3. The centering and gap-fixing connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: One end of the positioning block (33) is tapered.

4. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: The external connecting sleeve (4) is configured to be convex.

5. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: One end of the inner connecting sleeve (3) is provided with a groove that matches the protrusion of the outer connecting sleeve (4).

6. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: Spiral guide grooves are provided on the inner sides of both the inner stepped hole (32) and the outer stepped hole (42).

7. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: The external thread (41) and internal thread (31) are configured as trapezoidal threads.

8. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: The diameter of the inner stepped hole (32) is larger than the outer wall diameter of the inner tube (1).

9. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: The diameter of the outer stepped hole (42) is larger than the outer wall diameter of the outer tube (2).

10. A centering and gap-fixed connecting pipe fitting for connecting the inner and outer tubes of a coaxial heat exchanger according to claim 1, characterized in that: The contact surface between the positioning block (33) and the outer connecting sleeve (4) is provided with an annular welding groove. The cross-sectional shape of the annular welding groove is adapted to the conical end of the positioning block (33) to accommodate the solder and form a surrounding sealed welding structure.

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