A diesel engine exhaust system adapter pipe with a composite seal structure and a method of assembling the same

Abstract

The application discloses a diesel engine exhaust system plug-in pipe with a composite sealing structure and an assembling method thereof. The plug-in pipe comprises a plug-in pipe body and a composite sealing assembly arranged on the plug-in pipe body. The composite sealing assembly is arranged at the connection between the plug-in pipe body and the end of the exhaust pipe inner hole and the exhaust transition pipe. The composite sealing assembly comprises a J-shaped sealing ring and a laminated sealing ring. The plug-in pipe body is in a straight-through structure. A plurality of sealing ring grooves are arranged on the outer cylindrical surface of the plug-in pipe body in the axial direction, and are used for mounting the composite sealing assembly. The end of the plug-in pipe, the end of the exhaust pipe inner hole and the end of the exhaust transition pipe inner hole are all provided with a 2*30° insertion chamfer, and the end is provided with an R1 round corner, so that the exhaust flow resistance is reduced and the vortex generation is inhibited. The diesel engine exhaust system plug-in pipe solves the problem that the single-layer stainless steel laminated sealing ring cannot be completely expanded and cannot form an effective seal between the exhaust pipe and the exhaust transition pipe under the low-temperature and low-load conditions of the diesel engine.

Description

Technical Field

[0001] This invention relates to the field of engine exhaust system technology, and in particular to a diesel engine exhaust system connector with a composite sealing structure and its assembly method. Background Technology

[0002] The exhaust pipe of a certain model of high-power four-stroke high-efficiency diesel engine adopts a split structure, consisting of a segmented exhaust pipe, a connector, a transition pipe, and a sealing ring. The original design of the connector used a connector and a single-layer radial stacked sealing ring installed on the connector. Due to the influence of high temperature, high pressure exhaust airflow, continuous vibration, and different engine load conditions, the exhaust pipe, transition pipe, connector, and sealing ring are deformed, reducing the sealing performance and causing quality problems such as air leakage and oil leakage. This results in an imbalance between the engine's intake and exhaust, incomplete combustion, and reduced power output. In severe cases, it can cause the supporting equipment to malfunction.

[0003] In the prior art, the structural assembly diagram of the exhaust pipe, transition pipe, and insertion pipe is as follows: Figure 1 As shown; a schematic diagram of the unmodified assembly of the stacked sealing ring and the insertion tube, as shown. Figure 2 As shown. The original segmented exhaust pipes were connected using an insert pipe + single-layer radial stacked sealing ring method. The main technical defects of the structural design are as follows:

[0004] (1) The plug pipe component (plug pipe and single-layer sealing ring) is installed on the exhaust pipe. Under long-term use or different working conditions (withstanding high temperature, high pressure exhaust gas flow and continuous vibration), it may deform, age and wear, resulting in a decrease in sealing effect; the sealing effect decreases significantly under low speed conditions, resulting in gas leakage.

[0005] (2) The assembly of the plug pipe components (the fit between the plug pipe and the sealing ring) requires high installation accuracy. The assembly process of the exhaust pipe and the plug pipe components is carried out in the inner cavity of the exhaust pipe, which has low visibility and high assembly difficulty, and puts forward high requirements for the technical level of workers.

[0006] (3) The influence of the structure and material thermal expansion coefficient of the connector on the sealing performance under different engine operating conditions is shown in the table below.

[0007]

[0008] Comprehensive analysis shows that the original connector structure design cannot meet the reliability requirements of the product design.

[0009] In view of this, there is an urgent need for a composite sealing structure device for engine exhaust pipes that can suppress the deformation of the connection between the pipe components and the exhaust pipe under high temperature, high pressure, continuous vibration and different load conditions, improve sealing performance and thus meet design requirements. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by providing a composite sealing structure device for engine exhaust pipes. By optimizing the pipe structure, composite sealing ring design, and assembly process, this invention solves the problem of single-layer stacked sealing ring failure under low temperature and low operating conditions in diesel engines, improves the sealing reliability of the pipe and exhaust pipe, reduces exhaust leakage, and meets the requirements of mass production and long-term stable operation.

[0011] To achieve the above objectives, one aspect of this application provides a diesel engine exhaust system connector with a composite sealing structure, comprising: a connector body, which is an integral straight-through cylindrical structure, with multiple sets of first sealing ring grooves arranged axially on its outer cylindrical surface; the connector body is used to connect two exhaust pipes; a J-type sealing ring is disposed in the second sealing ring grooves at both ends of the connector body; and a stacked sealing ring is disposed in the first sealing ring groove; wherein, after the connector body is connected to the exhaust pipe, the J-type sealing ring and the stacked sealing ring are located at the insertion connection between the two; both ends of the connector body are machined with a 2×30° chamfer and a radius of radius R1, and the ends of the inner holes of the exhaust pipe and the exhaust transition pipe are simultaneously machined with the same chamfer and radius of radius R1; the inner and outer circles of the J-type sealing ring are tightly fitted with the inner holes of the exhaust pipe and the exhaust transition pipe, respectively, and the sealing elasticity is provided by the sealing ring itself; the stacked sealing ring comprises two single-layer stacked sealing rings, and the radial clearance between the inner diameter and outer diameter of the stacked sealing ring and the corresponding first sealing ring groove is 0.05-0.2 mm.

[0012] According to the embodiments of this application, the stacked sealing ring is a stacked sealing ring made of double-layer 310 stainless steel. The total thickness of the stacked sealing ring is adapted to the width of the ring groove, and the total compression is controlled between 10% and 30%.

[0013] According to an embodiment of this application, the first sealing ring groove is an annular groove axially arranged along the outer cylindrical surface of the insertion pipe body; the second sealing ring groove is an annular groove with an L-shaped cross-section formed by the inward contraction of the two ends of the insertion pipe body.

[0014] According to an embodiment of this application, the J-type sealing ring is made of high-temperature alloy material and coated with a TiAlCrN composite coating, forming a radial sealing structure.

[0015] According to an embodiment of this application, the J-type sealing ring and the main body of the insertion pipe are interference fit. The interference between the diameter of the J-type sealing ring and the inner diameter of the fitting satisfies the following: 0.10-0.15mm when the diameter is 30-60mm, and 0.15-0.20mm when the diameter is 60-100mm, thereby achieving dual sealing of gas and liquid.

[0016] According to an embodiment of this application, the insertion depth of the insertion pipe body into the exhaust pipe satisfies 0.35D, where D is the diameter of the insertion pipe body.

[0017] According to the embodiments of this application, the main body of the insertion pipe, the exhaust pipe, and the exhaust transition pipe are all made of medium silicon ferrite.

[0018] According to the embodiments of this application, the inner and outer circles of the J-type sealing ring are tightly fitted with the inner holes of the exhaust pipe and the exhaust transition pipe, respectively. The opening of the J-type sealing ring is installed facing outward, with no macroscopic leakage channel, thus achieving dual sealing of gas and liquid.

[0019] According to embodiments of this application, the high temperature resistance of the stacked sealing ring is ≤850℃.

[0020] Another aspect of this application discloses an assembly method applied to a diesel engine exhaust system connector with a composite sealing structure as described above, comprising the following steps:

[0021] S1: Assemble a stacked sealing ring:

[0022] (1) Pretreatment: Clean the surface of the annular groove of the insert pipe body to remove burrs, oil stains and oxide scale; check the appearance of the stacked sealing ring and verify that the inner diameter, outer diameter and thickness of the stacked sealing ring match the size of the annular groove.

[0023] (2) Rotation installation: Axially stretch the stacked sealing ring, first insert one end of the stacked sealing ring into the ring groove of the insert pipe body; use the spiral screwing method to evenly and smoothly screw the remaining part of the sealing ring into the ring groove;

[0024] (3) Post-assembly inspection: Check whether the sealing ring is fully embedded in the ring groove, without protrusions, warping, twisting or deformation; confirm that the compression of the sealing ring in the ring groove is uniform, without jamming or skew, and meets the design assembly requirements.

[0025] S2: Assemble the J-type sealing ring:

[0026] (1) Pre-assembly of tooling and insert pipe body: The positioning shaft is coaxially fixed and clamped at the opening at one end of the insert pipe body; the J-type sealing ring is installed on the guide body, and then the guide body is fitted into the guide bushing for clearance fit to form a sealing ring-guide assembly. The guide bushing of the above assembly is inserted from the other end opening of the insert pipe body so that the guide bushing is aligned with the end of the insert pipe.

[0027] (2) Tooling connection and axial preload: Insert the screw into the body of the insertion tube from the positioning shaft end, pass through the guide bushing, and axially preload the screw through the nut to keep the tooling components coaxial, reliably positioned, and without offset;

[0028] (3) The sealing ring is pushed into place: the guide bushing is moved axially, and the J-type sealing ring is pushed smoothly by the inner conical surface / end face of the guide bushing, so that the J-type sealing ring moves evenly along the outer wall of the insert pipe body until the J-type sealing ring is completely inserted into the target ring groove position of the insert pipe body, ensuring that the interference and position accuracy of the sealing ring meet the design requirements.

[0029] (4) Disassembly of tooling and inspection of finished product: Loosen the nut and pull out the screw; separate the guide body, guide bushing and positioning shaft in sequence, and separate the tooling from the assembled insertion pipe; check the installation status of the J-type sealing ring, and confirm that there is no twisting, no scratches, no positional deviation, the interference fit is uniform and meets the sealing design requirements.

[0030] The advantages of the present invention over the prior art are:

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. Composite sealing structure, reliable sealing: By combining double-layer stacked sealing rings with J-type sealing rings, the problem of traditional single-layer stacked rings failing to fully expand and seal in low temperature and low operating conditions is solved. This achieves high-reliability sealing of diesel engines under all operating conditions, from starting and idling, low speed and low load to high speed and high load. The high-load sealing effect is improved to over 95%, and the low-load sealing effect is improved to over 70%, eliminating exhaust leakage faults.

[0033] 2. Optimized structure: The 2×30° chamfer and R1 fillet design at the ends of the connector, exhaust pipe, and transition pipe effectively reduce exhaust airflow resistance, suppress vortex generation, and reduce airflow pressure loss; at the same time, the same material design ensures consistent thermal expansion, avoids sealing structure failure caused by thermal stress concentration, and improves long-term operational reliability.

[0034] 3. Good processability and suitable for mass production: The parameters such as the gap, compression amount, and interference of the sealing ring are all quantifiable process indicators, which facilitates the processing and assembly control in mass production and ensures product consistency; the assembly process of the composite sealing structure is simple and can realize the rapid docking of two exhaust pipes, improving assembly efficiency.

[0035] 4. Excellent material compatibility, high temperature resistance and corrosion resistance: The stacked sealing ring is made of 310 stainless steel, and the J-type sealing ring is made of high temperature alloy + TiAlCrN composite coating. It can adapt to exhaust high temperature of 150℃-750℃, exhaust back pressure of 0.3-0.75MPa and corrosive environment of sulfur-containing exhaust gas, meet the harsh working conditions of high-power diesel engines and extend the service life of the sealing structure. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the assembly of exhaust pipe components in the prior art;

[0037] Figure 2 This is a schematic diagram of the insertion pipe structure in the prior art;

[0038] Figure 3 This is a schematic diagram of the insertion tube structure as an example of the present invention;

[0039] Figure 4 This is a schematic diagram of the stacked sealing ring structure as an example of the present invention;

[0040] Figure 5 This is a schematic diagram of the J-type sealing ring structure as an example of the present invention;

[0041] Figure 6 This is a schematic diagram of the assembly of the exhaust pipe and the connector pipe, as exemplified by the present invention.

[0042] Figure 7 This is a schematic diagram illustrating the design of the insertion pipe and rounded corners when the exhaust pipe and insertion pipe are connected, as exemplified by the present invention.

[0043] Figure 8 This is a schematic diagram of the longitudinal section of the insertion tube as an example of the present invention;

[0044] Figure 9 This is an assembly tooling diagram of the insertion tube and the J-type sealing ring as an example of the present invention;

[0045] Figure 10 This is a schematic diagram illustrating the stress calculation of the insertion pipe model in the example of this invention;

[0046] Figure 11 This is a simulation diagram of the displacement calculation of the insertion pipe model in the example of this invention;

[0047] Figure 12 This is a schematic diagram of the strain calculation simulation of the insertion tube model in the example of this invention.

[0048] The annotations in the attached figures are explained as follows:

[0049] 1. Insertion pipe body, 2. Stacked sealing ring, 3. J-type sealing ring, 4. Exhaust pipe, 11. Positioning shaft, 12. Guide bushing, 13. Screw, 14. Nut, 15. Guide body. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0051] Please see Figures 3 to 8The diagram illustrates a diesel engine exhaust system connector with a composite sealing structure. It includes a connector body and a composite sealing assembly mounted on the connector body. The composite sealing assembly is located at the connection points between the connector body and the end of the exhaust pipe inner bore, and at the exhaust transition pipe. The composite sealing assembly includes a J-type sealing ring and a stacked sealing ring. The connector body has a straight-through structure, with multiple sets of sealing ring grooves axially arranged on its outer cylindrical surface for mounting the composite sealing assembly. The ends of the connector, the exhaust pipe inner bore, and the exhaust transition pipe inner bore are all provided with a 2×30° chamfer, and the ends are machined with an R1 fillet to reduce exhaust airflow resistance and suppress vortex generation. This diesel engine exhaust system connector solves the problem that single-layer stainless steel stacked sealing rings fail to fully expand and form an effective seal with the exhaust pipe and exhaust transition pipe under low-temperature and low-operating-condition conditions in diesel engines.

[0052] In this embodiment, as Figure 3 As shown, the main body of the connector is a straight-through cylindrical structure with multiple sets of first sealing ring grooves along the axial direction on its outer cylindrical surface; a stacked sealing ring is disposed in the first sealing ring groove; and a J-type sealing ring is disposed in the second sealing ring grooves at both ends of the connector body. After the connector body is connected to the exhaust pipe, the J-type sealing ring and the stacked sealing ring are located at the insertion connection point between the two.

[0053] Specifically, such as Figure 3 , Figure 8 As shown, the first sealing ring groove is an annular groove axially arranged along the outer cylindrical surface of the insertion pipe body; the second sealing ring groove is an annular groove with an L-shaped cross-section formed by the inward contraction of the two ends of the insertion pipe body.

[0054] Specifically, the J-type sealing ring is made of high-temperature alloy material and coated with a TiAlCrN composite coating, forming a radial sealing structure. The inner and outer circles of the J-type sealing ring are tightly fitted with the inner holes of the exhaust pipe and exhaust transition pipe, respectively. The sealing elasticity is provided by the sealing ring's own structure. The opening of the J-type sealing ring faces outwards during installation, eliminating leakage channels. Microscopic leakage is determined by the surface roughness of the manifold mounting ring location, enabling the sealing of both gas and liquid.

[0055] Specifically, the J-type sealing ring and the connector body are interference-fitted. The interference between the diameter of the J-type sealing ring and the inner diameter of the fitting meets the following requirements: 0.10-0.15mm for diameters of 30-60mm, and 0.15-0.20mm for diameters of 60-100mm, achieving dual sealing of gas and liquid. The precision assembly of the connector and sealing ring conforms to the cylindrical envelope principle of the sealing surfaces of the J-type sealing ring and the connector, meeting the design requirements.

[0056] Specifically, such as Figure 4As shown, the stacked sealing ring comprises two single-layer stacked sealing rings. The radial clearance between the inner and outer diameters of the stacked sealing rings and the corresponding grooves of the first sealing rings is 0.05-0.2 mm. The stacked sealing rings are made of double-layer 310 stainless steel. The total thickness of the stacked sealing rings is adapted to the width of the grooves, and the total compression is controlled between 10% and 30%. This structure of the stacked sealing ring has a high temperature resistance of ≤850℃ and features resistance to thermal creep, elastic compensation, vibration and shock, sintering, and corrosion. It can achieve approximately 95% sealing performance under high load conditions and approximately 70% sealing performance under low load conditions.

[0057] Specifically, such as Figure 7 As shown, based on the geometry of the connector, it is impossible to reduce the exhaust airflow resistance and vortex generation. Therefore, the insertion angle and end rounding of the inner bore of the exhaust pipe and transition pipe are designed to avoid vortexes generated by sharp corners. The design is completed on the connector, exhaust pipe, and transition pipe respectively. Preferably, both ends of the connector body are machined with a 2×30° chamfer and R1 fillet, and the ends of the exhaust pipe inner bore and the exhaust transition pipe inner bore are simultaneously machined with the same chamfer and R1 fillet.

[0058] In this embodiment, the insertion depth of the insertion pipe body into the exhaust pipe satisfies 0.35D, where D is the diameter of the insertion pipe body.

[0059] Specifically, the main body of the insertion pipe is made of straight-through medium silicon ferrite material, with a pipe diameter D=70mm, an insertion depth of 0.35D=24.5mm, and a corresponding insertion length L=28mm; the outer cylindrical surface of the insertion pipe is provided with 4 sets of sealing ring grooves, of which 2 sets are used to install stacked sealing rings and 2 sets are used to install J-type sealing rings; the end of the insertion pipe is machined with 2×30° chamfers and R1 fillets, and the ends of the inner holes of the exhaust pipe and exhaust transition pipe are machined with the same chamfers and fillets simultaneously.

[0060] Specifically, the main body of the connector, the exhaust pipe, and the exhaust transition pipe are all made of medium silicon ferrite.

[0061] Another aspect of this application discloses an assembly method applied to a diesel engine exhaust system connector with a composite sealing structure, comprising the following steps:

[0062] S1: Assemble a stacked sealing ring:

[0063] (1) Pretreatment: Clean the surface of the annular groove of the insert pipe body to remove burrs, oil stains and oxide scale; check the appearance of the stacked sealing ring and verify that the inner diameter, outer diameter and thickness of the stacked sealing ring match the size of the annular groove.

[0064] (2) Rotation installation: Axially stretch the stacked sealing ring, first insert one end of the stacked sealing ring into the ring groove of the insert pipe body; use the spiral screwing method to evenly and smoothly screw the remaining part of the sealing ring into the ring groove;

[0065] (3) Post-assembly inspection: Check whether the sealing ring is fully embedded in the ring groove, without protrusions, warping, twisting or deformation; confirm that the compression of the sealing ring in the ring groove is uniform, without jamming or skew, and meets the design assembly requirements.

[0066] S2: Assemble the J-type sealing ring. The overall assembly structure diagram using the tooling is shown below. Figure 9 As shown, the specific steps are as follows:

[0067] (1) Pre-assembly of tooling and insert pipe body: The positioning shaft is coaxially fixed and clamped at the opening at one end of the insert pipe body; the J-type sealing ring is installed on the guide body, and then the guide body is fitted into the guide bushing for clearance fit to form a sealing ring-guide assembly. The guide bushing of the above assembly is inserted from the other end opening of the insert pipe body so that the guide bushing is aligned with the end of the insert pipe.

[0068] (2) Tooling connection and axial preload: Insert the screw into the body of the insertion tube from the positioning shaft end, pass through the guide bushing, and axially preload the screw through the nut to keep the tooling components coaxial, reliably positioned, and without offset;

[0069] (3) The sealing ring is pushed into place: the guide bushing is moved axially, and the J-type sealing ring is pushed smoothly by the inner conical surface / end face of the guide bushing, so that the J-type sealing ring moves evenly along the outer wall of the insert pipe body until the J-type sealing ring is completely inserted into the target ring groove position of the insert pipe body, ensuring that the interference and position accuracy of the sealing ring meet the design requirements.

[0070] (4) Disassembly of tooling and inspection of finished product: Loosen the nut and pull out the screw; separate the guide body, guide bushing and positioning shaft in sequence, and separate the tooling from the assembled insertion pipe; check the installation status of the J-type sealing ring, and confirm that there is no twisting, no scratches, no positional deviation, the interference fit is uniform and meets the sealing design requirements.

[0071] In this embodiment, the process of using the insertion tube is as follows: First, install the stacked sealing ring and the J-type sealing ring in the corresponding ring groove of the insertion tube in sequence, ensuring that the compression of the stacked sealing ring meets the requirement of 10%-30%, and the opening of the J-type sealing ring faces outward; then, insert the insertion tube with the assembled composite sealing assembly into the joint between the exhaust pipe and the exhaust transition pipe, with the insertion depth meeting the requirement of L=28mm, to complete the quick connection of the two exhaust pipe sections; after assembly, check the fit of the sealing ring to ensure that there is no jamming or gap, and to ensure the reliability of the seal.

[0072] Example 1: Verification of the composite sealing structure of the exhaust pipe through whole-machine testing

[0073] The sealing performance tests of the diesel engine exhaust system consist of static test verification and bench test verification, the main contents of which are as follows.

[0074] a) Static test verification

[0075] The exhaust pipe was placed on a platform, 2L of diesel fuel was poured in, and after standing for 10 hours, the leakage at the exhaust pipe connector was observed. It was verified that no leakage problem occurred.

[0076] b) Bench test verification

[0077] Phase 1: Run at idle speed (800r / min) for 5 hours, check for exhaust pipe leakage every hour, and conduct a 90-minute supplementary break-in test after idling.

[0078]

[0079] Test conclusion: No leakage was observed, and the design requirements are met.

[0080] Phase 2: Following the test specifications, the system operated for a total of 8 hours and 40 minutes to verify the impact of high-temperature external characteristics on the new sealing ring.

[0081]

[0082] Test conclusion: No leakage was observed, and the design requirements are met.

[0083] Phase 3: 30 hours of idling (800 rpm) operation, with exhaust pipe leakage checked every hour. Test conclusion: No leakage was observed, meeting design requirements.

[0084] Verified by the whole machine bench test, the composite sealing structure showed no exhaust leakage in the entire operating range of the diesel engine (from start-up and idling speed to rated power), and the sealing performance met the design requirements. After the cyclic thermal shock test at 150℃-750℃, the sealing structure showed no failure or leakage, and the long-term operation reliability was excellent, meeting the requirements of mass production.

[0085] The whole-machine test verified the composite sealing structure of the exhaust pipe. The sealing effect reached more than 99.8% under the conditions of diesel engine starting and idling or low speed, high speed and heavy load and different working conditions, which met the design requirements.

[0086] Example 2: Finite Element Simulation Analysis of Insertion Tube

[0087] This embodiment conducts finite element simulation analysis on the insertion pipe structure under high-temperature service conditions. Taking into account the combined effects of high-temperature environment, thermal stress coupling and external structural loads, a refined tetrahedral mesh finite element calculation model of the insertion pipe is established, and multi-physics field coupled simulation calculations of structural stress, displacement and strain are completed based on the WCS coordinate system.

[0088] like Figures 10-12 As shown, the maximum shear stress peak of the insertion pipe structure is 5.40328 MPa. The high stress area is concentrated at the end sealing step structure, while the stress level in the main cylinder area is in a lower range. The overall stress distribution is uniform and gentle, with no risk of local stress concentration exceeding the standard. The maximum total structural displacement is only 3.0663 × 10⁻⁶ MPa. −4 The deformation amplitude is extremely small, with a diameter of mm, effectively ensuring the assembly accuracy and sealing reliability of the connector; the maximum principal strain of the structure is 1.101 × 10 mm. −5 Both the overall plastic deformation and elastic deformation are within the allowable range of material safety.

[0089] After multi-dimensional mechanical performance verification, under the coupled conditions of high temperature, thermal stress and composite load, the stress, deformation and strain of this plug pipe structure all meet the design specifications and usage requirements for long-term high-temperature service of the product, and the structural mechanical stability and service safety meet the engineering application standards.

[0090] In summary, the technical solution of this application has the following beneficial effects:

[0091] 1. Composite sealing structure, reliable sealing: By combining double-layer stacked sealing rings with J-type sealing rings, the problem of traditional single-layer stacked rings failing to fully expand and seal in low temperature and low operating conditions is solved. This achieves high-reliability sealing of diesel engines under all operating conditions, from starting and idling, low speed and low load to high speed and high load. The high-load sealing effect is improved to over 95%, and the low-load sealing effect is improved to over 70%, eliminating exhaust leakage faults.

[0092] 2. Optimized structure: The 2×30° chamfer and R1 fillet design at the ends of the insertion pipe, exhaust pipe, and transition pipe effectively reduce exhaust airflow resistance, suppress vortex generation, and reduce airflow pressure loss; at the same time, the same material design ensures consistent thermal expansion, avoids sealing structure failure caused by thermal stress concentration, and improves long-term operational reliability.

[0093] 3. Good processability and suitable for mass production: The parameters such as the gap, compression amount, and interference of the sealing ring are all quantifiable process indicators, which facilitates the processing and assembly control in mass production and ensures product consistency; the assembly process of the composite sealing structure is simple and can realize the rapid docking of two exhaust pipes, improving assembly efficiency.

[0094] 4. Excellent material compatibility, high temperature resistance and corrosion resistance: The stacked sealing ring is made of 310 stainless steel, and the J-type sealing ring is made of high temperature alloy + TiAlCrN composite coating. It can adapt to exhaust high temperature of 150℃-750℃, exhaust back pressure of 0.3-0.75MPa and corrosive environment of sulfur-containing exhaust gas, meet the harsh working conditions of high-power diesel engines and extend the service life of the sealing structure.

[0095] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A diesel engine exhaust system connector with a composite sealing structure, characterized in that, include: The main body of the insertion pipe is a straight cylindrical structure, and its outer cylindrical surface is provided with multiple sets of first sealing ring grooves along the axial direction. The connector body is used to connect two exhaust pipe sections; J-type sealing rings are disposed in the second sealing ring grooves at both ends of the insertion tube body; A stacked sealing ring is disposed in the first sealing ring groove; Wherein, after the main body of the insertion pipe is connected to the exhaust pipe, the J-type sealing ring and the stacked sealing ring are located at the insertion connection between the two; The ends of both ends of the connector body are machined with 2×30° chamfers and R1 fillets, and the ends of the exhaust pipe inner hole and the exhaust transition pipe inner hole are machined with the same chamfers and R1 fillets simultaneously. The inner and outer circles of the J-shaped sealing ring are tightly fitted with the inner holes of the exhaust pipe and the exhaust transition pipe, respectively, and the sealing elasticity is provided by the structure of the sealing ring itself. The stacked sealing ring comprises two single-layer stacked sealing rings, and the radial clearance between the inner diameter and outer diameter of the stacked sealing ring and the corresponding first sealing ring groove is 0.05-0.2 mm.

2. The diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The stacked sealing ring is made of double-layer 310 stainless steel. The total thickness of the stacked sealing ring is adapted to the width of the ring groove, and the total compression is controlled between 10% and 30%.

3. A diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The first sealing ring groove is an annular groove arranged axially along the outer cylindrical surface of the insertion pipe body; the second sealing ring groove is an annular groove with an L-shaped cross-section formed by the inward indentation of the two ends of the insertion pipe body.

4. A diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The J-type sealing ring is made of high-temperature alloy material and coated with TiAlCrN composite coating, and is a radial sealing structure.

5. A diesel engine exhaust system connector with a composite sealing structure according to claim 4, characterized in that, The J-type sealing ring and the insert pipe body are interference fit. The interference between the diameter of the J-type sealing ring and the inner diameter of the fitting is satisfied as follows: 0.10-0.15mm when the diameter is 30-60mm, and 0.15-0.20mm when the diameter is 60-100mm, so as to achieve dual sealing of gas and liquid.

6. A diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The insertion depth of the main body of the insertion pipe into the exhaust pipe satisfies 0.35D, where D is the diameter of the insertion pipe.

7. A diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The main body of the insertion pipe, the exhaust pipe, and the exhaust transition pipe are all made of medium silicon ferrite.

8. A diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The inner and outer circles of the J-type sealing ring are tightly fitted with the inner holes of the exhaust pipe and the exhaust transition pipe, respectively. The opening of the J-type sealing ring is installed facing outward, with no macroscopic leakage channel, thus achieving dual sealing of gas and liquid.

9. A diesel engine exhaust system connector with a composite sealing structure according to claim 1, characterized in that, The high temperature resistance of the stacked sealing ring is ≤850℃.

10. An assembly method applied to a diesel engine exhaust system connector with a composite sealing structure as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Assemble a stacked sealing ring: (1) Pretreatment: Clean the surface of the annular groove of the connector body to remove burrs, oil stains and oxide scale; check the appearance of the stacked sealing ring and verify that the inner diameter, outer diameter and thickness of the stacked sealing ring match the size of the annular groove. (2) Rotation installation: axially stretch the stacked sealing ring, and first insert one end of the stacked sealing ring into the ring groove of the insert pipe body; use a spiral screwing method to evenly and smoothly screw the remaining part of the sealing ring into the ring groove; (3) Post-assembly inspection: Check whether the sealing ring is fully embedded in the ring groove, without protrusions, warping, twisting or deformation; confirm that the compression of the sealing ring in the ring groove is uniform, without jamming or skew, and meets the design assembly requirements. S2: Assemble the J-type sealing ring: (1) Pre-assembly of tooling and insert pipe body: The positioning shaft is coaxially fixed and clamped at the opening at one end of the insert pipe body; the J-type sealing ring is installed on the guide body, and then the guide body is fitted into the guide bushing for clearance fit to form a sealing ring-guide assembly. The guide bushing of the above assembly is inserted from the other end opening of the insert pipe body so that the guide bushing is aligned with the end of the insert pipe. (2) Tooling connection and axial preload: Insert the screw into the body of the insertion tube from the positioning shaft end, pass through the guide bushing, and axially preload the screw through the nut to keep the tooling components coaxial, reliably positioned, and without offset; (3) The sealing ring is pushed into place: the guide bushing is moved axially, and the J-shaped sealing ring is pushed smoothly by the inner conical surface / end face of the guide bushing, so that the J-shaped sealing ring moves evenly along the outer wall of the insertion pipe body until the J-shaped sealing ring is completely inserted into the target ring groove position of the insertion pipe body, ensuring that the interference and position accuracy of the sealing ring meet the design requirements. (4) Disassembly of tooling and inspection of finished product: Loosen the nut and pull out the screw; separate the guide body, guide bushing and positioning shaft in sequence, and separate the tooling from the assembled insertion pipe; check the installation status of the J-type sealing ring, and confirm that there is no twisting, no scratches, no positional deviation, uniform interference fit, and meets the sealing design requirements.

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