R744 heat pump air conditioner pipeline joint sealing structure

Abstract

The invention discloses an R744 heat pump air conditioner pipeline connector sealing structure which comprises an aluminum pipe, a bolt, a male head pressing plate, a U-shaped metal sealing ring and a female head pressing plate. The male head pressing plate and the female head pressing plate are connected together through a bolt, a male head butt-joint through hole and a male head bolt through hole are formed in the male head pressing plate, and a female head butt-joint through hole and a female head threaded through hole are formed in the female head pressing plate; outer side ports of the male head butt-joint through hole and the female head butt-joint through hole are respectively connected with the aluminum pipe, and inner side ports of the male head butt-joint through hole and the female head butt-joint through hole are in butt joint by adopting a three-stage step positioning structure; the section of the U-shaped metal sealing ring is in a U-shaped groove shape, and the U-shaped metal sealing ring is assembled at the end of an inner side port of the male head butt-joint through hole in an interference mode and forms multi-face sealing with a step face of an inner side port of the female head butt-joint through hole. The problem of sealing leakage of the R744 system under the low-temperature and high-pressure working conditions can be solved, meanwhile, the process feasibility and large-batch production requirements are met, and the risk of system leakage is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of R744 (carbon dioxide) heat pump air conditioning system, in particular to a pipe joint sealing structure for R744 heat pump air conditioner, which is especially suitable for reliable sealing scene under low temperature and high pressure working condition. BACKGROUND

[0002] As an environmentally friendly refrigerant, R744 has become the preferred refrigerant for heat pump air conditioning systems due to its zero ozone depletion potential and extremely low global warming potential. However, R744 exhibits significant low temperature and high pressure characteristics during system operation, with working pressure often reaching 3-5 times that of traditional refrigerant systems. Moreover, the CO2 molecule has a diameter of only 0.33 nm, making it extremely susceptible to leakage through sealing gaps or material micropores, and the annual leakage rate must be strictly controlled below 0.5 g to meet usage requirements.

[0003] The existing pipe joint sealing structure of R744 air conditioning system mainly has the following defects: first, the traditional O-ring seal is prone to extrusion deformation under high pressure, leading to sealing failure, especially under pressure fluctuations caused by system start-stop, the sealing reliability decreases dramatically; second, although the red copper gasket seal can withstand high pressure, it is prone to problems such as tight sealing surface under low temperature working conditions (the minimum temperature of R744 system can reach below -40℃); third, ordinary rubber sealing materials (such as ordinary nitrile rubber) are prone to swelling, hardening or cracking under the action of R744 medium and high-low temperature cycles, which cannot guarantee long-term sealing performance.

[0004] In addition, the existing sealing structure adopts a multi-component superposition design, which has a complex assembly process and requires extremely high installation torque, increasing production costs and being not conducive to quality control in mass production. Therefore, developing a pipe joint sealing structure that is suitable for R744 system working conditions, reliable in sealing, easy to assemble and suitable for mass production has become a technical problem to be solved in the field. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a R744 heat pump air conditioner pipe joint sealing structure, which aims to solve the sealing leakage problem of R744 system under low temperature and high pressure working condition, while meeting the process feasibility and mass production requirements, and solving the system leakage problem.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a R744 heat pump air conditioner pipe joint sealing structure, comprising an aluminum pipe, a bolt, a male head pressing plate, a U-shaped metal sealing ring and a female head pressing plate;

[0007] The male head pressing plate and the female head pressing plate are connected together by the bolt, the male head pressing plate is provided with a male head butt joint through hole and a bolt assembly through hole, and the female head pressing plate is provided with a female head butt joint through hole and a threaded hole;

[0008] The outer side ports of the male and female butt joint through holes are connected with aluminum pipes, and the inner side ports of the male and female butt joint through holes are butt jointed by using a three-stage positioning structure;

[0009] The cross section of the U-shaped metal sealing ring is in a U-shaped groove shape, the U-shaped metal sealing ring is interference fitted at the end of the inner side port of the male butt joint through hole, and forms multi-surface sealing with the inner side port step surface of the female butt joint through hole.

[0010] Further, a positioning boss is arranged on the inner end face of the side of the male head pressing plate away from the butt joint through hole, the positioning boss is attached to the supporting surface of the female head pressing plate to form a fulcrum, and the sealing surface pressure is amplified by lever effect when the bolt is fastened.

[0011] Further, the U-shaped metal sealing ring is a composite structure of a metal framework and a rubber coating, the metal framework is made of stainless steel and has a thickness of 0.1-0.3 mm, and the rubber coating is sprayed on the surface of the metal framework and is made of one of hydrogenated nitrile rubber, nitrile rubber and fluororubber and has a thickness of 0.02-0.1 mm.

[0012] Further, the U-shaped metal sealing ring is provided with an inner side sealing surface, a top sealing surface, an outer side sealing surface and an opening supporting end surface.

[0013] Further, the inner side sealing surface is interference fitted with the end side wall at the second stage step of the male head pressing plate, and the interference amount is 0.01-0.03 mm.

[0014] Further, the outer side sealing surface is in contact with the axial inclined surface at the second stage step of the female head pressing plate, and the axial inclined surface has an inclination angle of 5°-30°.

[0015] Further, the top sealing surface is in contact with the sealing boss on the second stage step of the male head pressing plate to form high pressure surface sealing.

[0016] A preparation method of the U-shaped metal sealing ring, the framework of the sealing ring is made of a 0.2 mm thick 301 stainless steel strip, FKM rubber and vulcanizing agent are mixed in a ratio of 100:2, the surface of the framework is coated by using electrostatic spraying process, the coating thickness is controlled to be 0.05 mm, and then the stable rubber layer is formed by vulcanization at 160℃ for 20 minutes; then the stainless steel strip with coating is formed into a U-shaped groove structure by stamping; wherein the opening width of the U-shaped groove is 2 mm, and the groove depth is 1.3 mm.

[0017] An assembly method of the R744 heat pump air conditioner pipeline joint sealing structure as described above, the U-shaped metal sealing ring is sleeved into the inner side port end of the male head pressing plate, and is pressed and assembled to the top sealing surface of the sealing ring and the sealing boss of the male head pressing plate; then the male head pressing plate and the female head pressing plate are aligned and positioned, the positioning boss of the male head pressing plate is aligned with the supporting surface of the female head pressing plate, then the bolt is inserted and pre-tightened, and then a torque wrench is used to fasten at a standard torque of 8-12 N·m, and the assembly is completed; in addition, the aluminum pipe is connected with the male head pressing plate and the female head pressing plate through a laser welding process, so that the sealing property is ensured.

[0018] Compared with the prior art, the present application has the following significant advantages:

[0019] (1) High sealing reliability: the U-shaped sealing ring structure of "metal framework + rubber coating" is adopted, combined with multi-surface extrusion sealing design, to realize three times of sealing protection. The 301 stainless steel framework can withstand the high pressure impact of the R744 system, the rubber coating fills the micro gap of the sealing surface, and the inclined surface self-tightening structure is used, so that the leakage rate is reduced to less than 1 / 10 of the traditional joint, and the leakage control requirement of ≤0.5 g / year is met.

[0020] (2) Strong working condition adaptability: the 301 stainless steel still has high yield strength and good toughness at-40 DEG C low temperature, and the FKM rubber coating can withstand temperature cycles of-40 DEG C to 165 DEG C, which is fully suitable for the extreme working conditions of the R744 heat pump air conditioner, and solves the problems of low-temperature embrittlement and high-temperature failure of traditional sealing materials.

[0021] (3) Simple and efficient assembly: the lever type pressing structure reduces the bolt fastening torque requirement; the structure of each component is standardized, and is suitable for automatic production line batch assembly.

[0022] (4) Controllable cost: the core materials are selected from conventional 301 stainless steel and FKM rubber, without special rare materials; the structure design is simple, and the number of parts is reduced, and the comprehensive cost is reduced by about 30% compared with the existing red copper sealing structure. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 is a schematic view of the sealing structure before overall assembly of the present application;

[0024] Fig. 2 is a schematic view of the sealing structure after overall assembly of the present application;

[0025] Fig. 3 is a schematic view of the cross section of the sealing structure after overall assembly of the present application

[0026] Fig. 4 is a schematic view of the cross section of the male head pressing plate structure;

[0027] Fig. 5 is a schematic view of the cross section of the U-shaped metal sealing ring structure;

[0028] Fig. 6 is a schematic view of the structure of the female head pressing plate section;

[0029] Fig. 7 is a partial enlarged view of the sealing structure.

[0030] Reference signs: 1-aluminum pipe, 2-bolt, 3-male head pressing plate, 3a-positioning boss, 3b-bolt assembly through hole, 3c-sealing boss, 3d-male head butt joint through hole, 3e-end side wall, 3f-male head pressing plate and aluminum pipe connecting groove, 4-U-shaped metal sealing ring, 4a-outer opening support end face, 4b-inner opening support end face, 4c-inner sealing surface, 4d-outer sealing surface, 4e-top sealing surface, 5-female head pressing plate, 5a-supporting surface, 5b-thread hole, 5c-step radial surface, 5d-step axial inclined surface, 5e-female head pressing plate and aluminum pipe connecting groove. DETAILED DESCRIPTION

[0031] The application will be described in detail below in combination with the drawings and specific embodiments.

[0032] As shown in the drawings, Figs. 1 to 7 a sealing structure of an R744 heat pump air conditioner pipeline joint, comprising an aluminum pipe 1, a bolt 2, a male head pressing plate 3, a U-shaped metal sealing ring 4 and a female head pressing plate 5; the male head pressing plate 3 and the female head pressing plate 5 are connected together by the bolt 2, the male head pressing plate 3 is provided with a male head butt joint through hole 3d and a male head bolt through hole 3b, and the female head pressing plate 5 is provided with a female head butt joint through hole and a female head thread through hole 5b; the outer ports of the male head butt joint through hole and the female head butt joint through hole are connected with the aluminum pipe 1 respectively, and the inner ports of the male head butt joint through hole and the female head butt joint through hole are butt jointed by using a three-step positioning structure; the cross section of the U-shaped metal sealing ring 4 is in the shape of a U-shaped groove, the U-shaped metal sealing ring 4 is interference-fitted at the end of the inner port of the male head butt joint through hole, and forms a multi-surface sealing with the inner port step surface of the female head butt joint through hole.

[0033] 1, U-shaped metal sealing ring structure parameter explanation:

[0034] The U-shaped metal sealing ring (reference sign 4) is provided with an inner sealing surface 4c, a top sealing surface 4e, an outer sealing surface 4d and an opening support end face, and its structure is in the shape of a U-shaped groove, and has a bidirectional deformation compensation capacity. The sealing ring adopts a “metal framework + rubber coating” composite structure:

[0035] The material of the metal framework is selected from 301 austenitic stainless steel, which can effectively resist the high pressure impact of the R744 system; the thickness of the stainless steel layer is designed to be 0.1-0.3 mm, and the optimal thickness is 0.2 mm, which can not only ensure the structural rigidity but also has a certain elastic deformation capacity.

[0036] The rubber coating is sprayed onto the surface of the metal skeleton. The material is selected from HNBR (hydrogenated nitrile rubber), NBR (nitrile rubber), and KFM (fluororubber), which are resistant to R744 media and have excellent high and low temperature stability. Among them, FKM is preferred as the material for high temperature conditions (≤165℃), and its wear resistance and chemical corrosion resistance are significantly better than ordinary rubber. The thickness of the rubber layer is 0.03~0.1mm, with an optimal thickness of 0.05mm, which can improve the sealing surface fit without affecting the strength of the metal skeleton.

[0037] 2. Assembly relationship and sealing principle explanation:

[0038] The assembly of the U-shaped metal sealing ring 4 and the male pressure plate 3 adopts an interference fit design: the inner sealing surface 4c of the sealing ring is tightly fitted with the end side wall 3e of the male pressure plate 3, and the interference is controlled at 0.01~0.03mm, which is less than the thickness of the rubber coating to avoid damage to the coating, while ensuring the initial seal; after assembly, the top sealing surface 4e of the sealing ring is completely fitted with the sealing surface of the sealing boss 3c of the male pressure plate 3, forming the first pre-seal.

[0039] The male pressure plate 3 and the female pressure plate 5 are fitted with a three-step positioning structure: the female pressure plate 5 has a groove with three steps, wherein the radial surface 5c of the second step contacts and positions the open support end face of the U-shaped metal sealing ring 4, and the axial inclined surface 5d of the second step is designed to be a 5°~30° inclined surface, forming a line contact fit with the outer sealing surface 4d of the sealing ring. The male pressure plate 3 has a bolt assembly through hole 3b, and the female pressure plate 5 has a threaded hole 5b at the corresponding position. The bolt 2 passes through the bolt assembly through hole 3b and is fastened to the threaded hole 5b.

[0040] The sealing process consists of two stages: In the first stage, when the bolts are initially tightened, the stepped radial surface 5c of the female pressure plate 5 presses against the opening support end face of the sealing ring, causing the U-shaped sealing ring opening to shrink. The top sealing surface 4e and the sealing boss 3c of the male pressure plate form a high-pressure surface seal, and the leakage rate can be controlled within 1×10⁻⁻⁶. 6 Below mbar·L / s; In the second stage, as the bolt torque increases (recommended torque value 8~12 N·m), the axial inclined surface 5d of the female head pressure plate generates an axial component force on the outer sealing surface 4d of the sealing ring, pushing the inner sealing surface 4c of the sealing ring to further press against the side wall 3e of the male head pressure plate. At the same time, the elastic deformation of the U-shaped structure causes the sealing surface to produce a self-tightening effect. The higher the pressure, the tighter the seal, which is fully compatible with the pressure characteristics of the R744 system.

[0041] The male pressure plate 3 has a positioning boss 3a at one end, which fits against the support surface 5a of the female pressure plate 5 to form a fulcrum. After assembly, the whole structure forms a lever structure. The torque applied by the bolt is amplified by the lever and acts on the sealing part, which can obtain a greater sealing clamping force under the same bolt torque, effectively reducing the assembly torque requirement and solving the problem of difficulty in applying force when working at height.

[0042] Typically, the male connector clamp is located at the end of the pipe, while the female connector clamp is located on the side of other components in the system.

[0043] 3. Preparation instructions:

[0044] The fabrication of this sealing structure includes:

[0045] (1) Preparation of U-shaped metal sealing ring: The skeleton is made of 0.2mm thick 301 stainless steel strip. FKM rubber and vulcanizing agent are mixed in a ratio of 100:2 and coated on the stainless steel surface by electrostatic spraying. The coating thickness is controlled at 0.05mm. Then, it is vulcanized at 160℃ for 20 minutes to form a stable rubber layer. The coated stainless steel strip is stamped into a U-shaped groove structure with a U-shaped groove opening width of 2mm and a groove depth of 1.3mm.

[0046] (2) Pressure plate processing: The male pressure plate 3 and the female pressure plate 5 are forged from 6061 aluminum alloy. The key sealing surfaces (3c, 3e, 5c, 5d) are precision ground, and the surface roughness is controlled below Ra1.6μm. The bolt through hole 3b and the threaded hole 5b are tapped and then rolled to improve the thread strength. Among them, the positioning boss 3a has a height of 1mm, the sealing boss 3c has a surface roughness of Ra1.6μm, and the axial slope angle of the female pressure plate step 5d is set to 5°.

[0047] (3) Assembly process: Insert the U-shaped metal sealing ring 4 into the end of the male pressure plate 3, and press it into place with the top sealing surface 4e and the sealing boss 3c using special tooling; align and position the male pressure plate and the female pressure plate, insert the bolt 2 for pre-tightening, and then use a torque wrench to tighten it with a standard torque of 8~12 N·m to complete the assembly.

[0048] 4. Performance Testing:

[0049] The assembled sealing structure underwent high and low temperature pressure pulse testing. The test conditions were: temperature cycling from -40℃ to 165℃, pressure fluctuation from 3MPa to 17MPa, pulse frequency of 0.25Hz, and 150,000 pulses. Test results showed no visible leakage at the sealing points. Leak detection using a high-pressure helium leak detector showed a leakage rate of 3.2 × 10⁻⁶ at 17MPa. -7 mbar·L / s, far below the industry standard requirements.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the scope of protection of the present invention in any way, and all technical solutions obtained by equivalent substitution or other means fall within the scope of protection of the present invention. Parts not covered in this invention are the same as or can be implemented using existing technology.

Claims

1. A sealing structure for an R744 heat pump air conditioning pipe joint, characterized in that, Includes aluminum tubing, bolts, male pressure plates, U-shaped metal sealing rings, and female pressure plates; The male head pressure plate and the female head pressure plate are connected together by bolts. The male head pressure plate has a male head mating through hole and a bolt assembly through hole, and the female head pressure plate has a female head mating through hole and a threaded hole. The outer ports of the male and female mating through holes are connected to aluminum tubes, and the inner ports of the male and female mating through holes are mated using a three-stage step positioning structure. The cross-section of the U-shaped metal sealing ring is U-shaped. The U-shaped metal sealing ring is interference-fitted to the end of the inner port of the male connector through hole and forms a multi-faceted seal with the stepped surface of the inner port of the female connector through hole.

2. The sealing structure for an R744 heat pump air conditioning pipe joint according to claim 1, characterized in that, The male pressure plate has a positioning boss on the inner end face away from the docking through hole. The positioning boss fits with the support surface of the female pressure plate to form a fulcrum. When the bolt is tightened, the pressure on the sealing surface is amplified through the leverage effect.

3. The sealing structure for an R744 heat pump air conditioning pipe joint according to claim 1, characterized in that, The U-shaped metal sealing ring is a composite structure of a metal skeleton and a rubber coating. The metal skeleton is made of stainless steel with a thickness of 0.1~0.3mm. The rubber coating is sprayed on the surface of the metal skeleton and is made of one of hydrogenated nitrile rubber, nitrile rubber, or fluororubber with a thickness of 0.02~0.1mm.

4. The sealing structure for an R744 heat pump air conditioning pipe joint according to claim 1, characterized in that, The U-shaped metal sealing ring has an inner sealing surface, a top sealing surface, an outer sealing surface, and an open support end face.

5. The sealing structure for an R744 heat pump air conditioning pipe joint according to claim 4, characterized in that, The inner sealing surface is interference-fitted with the end side wall of the male pressure plate at the second step, with an interference amount of 0.01~0.03mm.

6. The sealing structure for an R744 heat pump air conditioning pipe joint according to claim 4, characterized in that, The outer sealing surface is in contact with the axial inclined surface at the second step of the female head pressure plate, and the axial inclined surface has an inclination angle of 5°~30°.

7. The sealing structure for an R744 heat pump air conditioning pipe joint according to claim 4, characterized in that, The top sealing surface contacts the sealing boss on the secondary step of the male pressure plate to form a high-pressure surface seal.

8. The method for preparing the U-shaped metal sealing ring as described in any one of claims 1 to 7, characterized in that, The skeleton of the sealing ring is made of 0.2mm thick 301 stainless steel strip. FKM rubber and vulcanizing agent are mixed in a ratio of 100:2 and coated on the surface of the skeleton by electrostatic spraying. The coating thickness is controlled at 0.05mm. Then, it is vulcanized at 160℃ for 20 minutes to form a stable rubber layer. Then, the coated stainless steel strip is stamped into a U-shaped groove structure.

9. The method for preparing the U-shaped metal sealing ring according to claim 8, characterized in that, The U-shaped groove has an opening width of 2mm and a groove depth of 1.3mm.

10. The assembly method of the R744 heat pump air conditioning pipe joint sealing structure as described in any one of claims 1 to 7, characterized in that, Insert the U-shaped metal sealing ring into the inner end of the male pressure plate and press it in until the top sealing surface of the sealing ring fits against the sealing boss of the male pressure plate. Then align and position the male pressure plate and the female pressure plate, aligning the positioning boss of the male pressure plate with the support surface of the female pressure plate. Insert the bolts and pre-tighten them, then use a torque wrench to tighten them to a standard torque of 8~12 N·m to complete the assembly.

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