Natural gas egr valve seal structure

Abstract

The utility model provides a kind of natural gas EGR valve sealing structure, including the coaxial arrangement of valve shell, sliding bearing, sealing assembly, end cover and valve rod;Valve shell is provided with mounting hole along the axial direction;Sliding bearing is arranged in mounting hole;Sealing assembly is arranged in mounting hole and located the axial direction below sliding bearing;End cover is arranged in the valve shell mounting hole and located the axial direction above sliding bearing;Valve shell is coaxially provided with heat insulation cavity, the axial upper end of heat insulation cavity is communicated with the hole bottom of mounting hole, and the axial lower end of heat insulation cavity is provided with valve rod perforation;The valve rod is slidably arranged in sliding bearing along the axial direction.The utility model has the advantages that the structure is coaxially arranged by each core component, ensure the accuracy of valve rod axial sliding, reduce the deviation and wear in movement process, improve the operation stability of EGR valve;By valve shell integrated heat insulation cavity, high temperature when natural gas EGR valve works can be blocked to sealing assembly, sliding bearing key component transmission.

Description

Technical Field

[0001] This utility model relates to the field of natural gas EGR valve technology, and more specifically, to a natural gas EGR valve sealing structure. Background Technology

[0002] The EGR valve is a core component of the exhaust gas recirculation system in a natural gas engine, and its sealing performance directly affects the engine's emissions, power performance, and service life. Existing natural gas EGR valves typically include a valve body, mounting base, upper sliding bearing, lower sliding bearing, valve stem, sealing ring, end cap, and heat shield. The mounting base is located within the valve body, providing installation space for the sliding bearings and sealing ring. The upper and lower sliding bearings are mounted on the upper and lower sides of the mounting base, respectively. The valve stem moves up and down within the mounting base, supported by the two sliding bearings, to control the valve's opening and closing. To prevent exhaust gas from leaking into the external environment through the gaps between the valve stem, mounting base, and sliding bearings, the existing structure places the sealing ring at the top, above the upper sliding bearing, and the end cap on top of the mounting base to maintain the sealing ring's position. Additionally, a heat shield is installed between the valve body and the mounting base to protect the sliding bearings from the high-temperature exhaust gas. However, this existing sealing structure has the following significant drawbacks: The large number of parts leads to a long tolerance chain, which can easily cause concentricity deviations in related moving parts, resulting in uneven wear or jamming of the valve stem and valve plate, seriously affecting the service life of the EGR valve. The sealing ring is located at the very top of the entire structure. A large amount of water vapor and other corrosive substances contained in the exhaust gas may still enter the area between the mounting seat and the valve stem through the gap, causing corrosion to the mounting seat. The resulting corrosion products will further aggravate the valve stem jamming problem and affect the normal operation of the EGR valve. External heat shields increase the number of parts and assembly steps, and their mating surfaces with the valve body and mounting base may become new heat conduction paths and potential leakage points.

[0003] Therefore, there is an urgent need for a natural gas EGR valve sealing structure that is simplified, has reliable sealing, and has a long service life, in order to solve the above-mentioned problems existing in the current technology. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a new type of sealing structure for natural gas EGR valves. By optimizing the structural layout and integrated design, the number of parts is reduced, tolerance accumulation is reduced, and sealing and heat insulation effects are improved, thereby effectively solving the problems of valve stem wear, jamming, and corrosion, and improving the working reliability and service life of the EGR valve.

[0005] To achieve the purpose of this utility model, the following technical solution is adopted: A sealing structure for a natural gas EGR valve includes a valve body, a sliding bearing, a sealing assembly, an end cap, and a valve stem arranged coaxially. The valve body has an axially oriented mounting hole. The sliding bearing is disposed within the mounting hole. The sealing assembly is disposed within the mounting hole and located axially below the sliding bearing. The end cap is disposed within the mounting hole of the valve body and located axially above the sliding bearing, closing the opening of the mounting hole and limiting and fixing the sliding bearing and sealing assembly within the mounting hole. A heat insulation cavity is coaxially arranged within the valve body, with its upper axial end communicating with the bottom of the mounting hole, and a valve stem through-hole extending through the lower axial end of the heat insulation cavity. The valve stem slides axially through the sliding bearing, with its lower end passing through the end cap, sliding bearing, sealing assembly, heat insulation cavity, and valve stem through-hole sequentially from top to bottom. By adopting a coaxial configuration for each core component, the accuracy of the valve stem's axial sliding is ensured, reducing offset and wear during movement and improving the operational stability of the EGR valve. The sliding bearing and sealing assembly are limited and fixed within the mounting hole via end caps, resulting in a compact assembly structure that prevents seal failure or operational malfunctions caused by loose components, while also simplifying the assembly process. An integrated heat insulation cavity within the valve body prevents the high temperatures generated during natural gas EGR valve operation from being transmitted to critical components such as the sealing assembly and sliding bearing, delaying component aging and extending the service life of the sealing structure.

[0006] Preferably, the mounting holes are stepped, comprising a first stepped portion, a second stepped portion, and a third stepped portion, with the diameter decreasing sequentially from top to bottom and coaxially arranged. The sealing assembly is fixedly installed in the third stepped portion, the sliding bearing is fixedly installed in the second stepped portion, and the end cap is fixedly installed in the first stepped portion. The stepped design of the mounting holes, with the diameter decreasing from top to bottom, provides a precise layered installation and positioning structure for the end cap, sliding bearing, and sealing assembly, ensuring accurate assembly positions of each component and avoiding axial misalignment. Furthermore, each component is fixedly installed in its corresponding stepped portion, achieving independent positioning of the components, improving the structural stability after assembly, and facilitating disassembly and replacement during subsequent maintenance, thus reducing maintenance costs.

[0007] Preferably, the mounting hole further includes a fourth step coaxially disposed below the third step; the lower axial end of the fourth step communicates with the upper axial end of the insulation cavity, and the diameter of the fourth step is adapted to the outer diameter of the valve stem. The fourth step provides additional guiding support to the valve stem, further improving the smoothness of the valve stem's axial sliding and reducing contact wear between the valve stem and the sealing assembly or valve stem perforation; furthermore, the matching of the fourth step's diameter with the valve stem's outer diameter reduces the gap around the valve stem, lowering the risk of natural gas leakage, and preventing impurities from entering the insulation cavity or sealing assembly through the gaps, thus providing auxiliary sealing and protection.

[0008] Preferably, the sealing assembly includes an annular positioning frame and a sealing ring. The positioning frame is fitted onto the valve stem, and the sealing ring is fitted onto the positioning frame. The outer peripheral wall of the sealing ring abuts against the inner peripheral wall of the mounting hole, the inner peripheral wall of the sealing ring abuts against the outer peripheral wall of the positioning frame, and the inner peripheral wall of the positioning frame abuts against the outer peripheral wall of the valve stem to achieve a seal. By adopting a combination structure of "positioning frame + sealing ring" in the sealing assembly, the positioning frame can effectively support the sealing ring, preventing deformation and displacement of the sealing ring during valve stem sliding, thus ensuring sealing stability. The sealing ring forms multiple sealing defenses through double abutment with the inner peripheral wall of the mounting hole and the outer peripheral wall of the positioning frame, as well as the abutment between the positioning frame and the outer peripheral wall of the valve stem, significantly improving the sealing effect and effectively preventing natural gas leakage. Furthermore, the abutment between the positioning frame and the valve stem reduces direct friction between the sealing ring and the valve stem, delaying sealing ring wear and extending the service life of the sealing assembly.

[0009] Preferably, the outer peripheral wall of the positioning frame is provided with a concave arc surface along the circumferential direction. The curvature of the concave arc surface matches the curvature of the inner peripheral wall of the sealing ring, and the concave arc surface abuts against the inner peripheral wall of the sealing ring. By matching the curvature of the concave arc surface of the positioning frame's outer peripheral wall with the curvature of the inner peripheral wall of the sealing ring and abutting against it, the contact area between the two is increased, improving the positioning frame's limiting and fixing effect on the sealing ring and preventing the sealing ring from slipping or shifting. Furthermore, the conforming structure of the arc surface allows for more even stress distribution on the sealing ring, avoiding damage caused by localized stress concentration. It also enhances the sealing fit between the sealing ring and the positioning frame and mounting hole, further optimizing the sealing performance.

[0010] Preferably, the positioning frame is made of PTFE material. PTFE material has the characteristics of high and low temperature resistance, low coefficient of friction, and chemical corrosion resistance. As a positioning frame material, it can adapt to the high-temperature working environment of natural gas EGR valves, reducing frictional wear with valve stems and sealing rings. Furthermore, the stability of this material ensures that the positioning frame will not deform during long-term use, continuously providing reliable support for the sealing rings, ensuring the long-term effectiveness of the sealing structure, and improving the overall durability of the sealing structure.

[0011] Preferably, the sealing ring is made of rubber. Rubber material has good elasticity and sealing properties, and can tightly fit the positioning frame and the inner wall of the mounting hole through its own deformation, filling tiny gaps and improving the sealing effect; in addition, the elastic properties of rubber material can adapt to the sliding movement of the valve stem, reducing frictional damage to the sealing surface, while also having certain wear resistance and aging resistance, ensuring the long-term stable operation of the sealing assembly.

[0012] Preferably, the axial cross-section of the heat insulation cavity is an isosceles trapezoid, with the width of the lower base being smaller than the width of the upper base. This isosceles trapezoidal axial cross-section, with the lower base being narrower than the upper base, optimizes the internal structural layout of the valve housing while ensuring sufficient insulation space, reducing material usage and overall weight. Furthermore, the isosceles trapezoidal structure ensures more uniform stress distribution on the cavity walls, improving structural strength and facilitating heat dispersion and transfer, preventing localized high-temperature accumulation, enhancing insulation performance, and better protecting the upper sealing components and sliding bearings.

[0013] Preferably, the heat insulation cavity is integrally formed with the valve housing, and the cross-sectional width of the upper bottom of the heat insulation cavity is greater than the cross-sectional width of the sliding bearing. Integrating the heat insulation cavity with the valve housing reduces assembly gaps, lowers the risk of natural gas leakage, and improves the overall structural strength and stability, preventing the heat insulation cavity from detaching or loosening under high temperature and vibration conditions. Furthermore, the greater width of the upper bottom cross-section of the heat insulation cavity ensures sufficient heat insulation space below the sliding bearing, fully covering the corresponding areas of the sliding bearing and sealing components, improving the comprehensiveness of heat insulation protection, and further delaying the aging of critical components.

[0014] The advantages of this utility model are: Simplified structure and convenient assembly: By placing the sealing component below the sliding bearing and adopting an integrated stepped bore design, the number of independent parts is reduced, the tolerance chain is shortened, the concentricity and stability of the valve stem movement are improved, and the risk of uneven wear or jamming is reduced.

[0015] High sealing reliability: The sealing component is located below the sliding bearing, which can effectively prevent water vapor and corrosive substances in the high-temperature exhaust gas from entering the bearing area, avoiding valve stem jamming caused by the accumulation of corrosive substances.

[0016] Excellent thermal insulation performance: The integrated thermal insulation cavity is integrally molded with the valve body, reducing the heat conduction path and thermal bridge effect, effectively isolating high-temperature exhaust gas from transferring heat to the sliding bearing and sealing components, and extending the service life of the seals and bearings.

[0017] Dual optimization of guidance and sealing: The optional fourth step section is set as an auxiliary guide structure for the valve stem to further improve motion stability; the matching design of the positioning skeleton and the sealing ring enhances the sealing fit and durability.

[0018] Reasonable material selection: The PTFE skeleton has good high temperature resistance, corrosion resistance and self-lubricating properties; the rubber sealing ring has good elasticity and reliable sealing. The combination of the two is suitable for the harsh working conditions of EGR valve in high temperature and corrosion. Attached Figure Description

[0019] Figure 1 is a schematic diagram of the sealing structure of the natural gas EGR valve of this utility model.

[0020] Figure 2 is a schematic diagram of the valve housing of this utility model.

[0021] Explanation of reference numerals in the attached figures: 1. Valve body; 10. Mounting hole; 101. Orifice; 102. Bottom of hole; 11. First step; 12. Second step; 13. Third step; 14. Fourth step; 2. Sliding bearing; 31. Positioning frame; 32. Sealing ring; 33. Arc concave surface; 4. End cap; 5. Valve stem; 6. Insulation cavity; 7. Valve stem perforation. Detailed Implementation

[0022] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0023] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0024] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 and Figure 2As shown, a natural gas EGR valve sealing structure includes a valve body 1, a sliding bearing 2, a sealing assembly, an end cap 4, and a valve stem 5 arranged coaxially. The upper end face of the valve body 1 has an axially oriented mounting hole 10 (vertical direction in the figure). The sliding bearing 2 is axially positioned within the mounting hole 10. The sealing assembly is positioned within the mounting hole 10 and located axially below the sliding bearing 2. The end cap 4 is positioned within the mounting hole 10 of the valve body 1 and located axially above the sliding bearing 2, and the end cap 4 closes the opening 101 of the mounting hole 10, limiting and fixing the sliding bearing 2 and the sealing assembly within the mounting hole 10. A heat insulation cavity 6 is coaxially arranged within the valve body 1. The upper axial end of the heat insulation cavity 6 communicates with the bottom 102 of the mounting hole 10, and the lower axial end of the heat insulation cavity 6 has a valve stem through-hole 7. The valve stem 5 slides axially within the sliding bearing 2, and the lower end of the valve stem 5 passes sequentially from top to bottom through the end cap 4, the sliding bearing 2, the sealing assembly, the heat insulation cavity 6, and the valve stem through-hole 7. This structure ensures the accuracy of axial sliding of the valve stem 5 by coaxially aligning the core components—valve housing 1, sliding bearing 2, sealing assembly, end cap 4, and valve stem 5—reducing offset and wear during operation and improving the operational stability of the EGR valve. The end cap 4 within the mounting hole 10 provides limiting and fixing for the sliding bearing 2 and sealing assembly, resulting in a compact assembly structure that prevents sealing failure or operational malfunctions caused by component loosening, while also simplifying the assembly process. The integrated heat insulation cavity 6 within the valve housing 1 prevents the high temperatures generated during EGR valve operation from being transmitted to critical components such as the sealing assembly and sliding bearing 2, delaying component aging and extending the service life of the sealing structure.

[0027] like Figures 1 to 2 As shown, the mounting hole 10 is stepped, comprising a first stepped portion 11, a second stepped portion 12, and a third stepped portion 13, with the diameter decreasing sequentially from top to bottom and coaxially arranged. The sealing assembly is fixedly installed within the third stepped portion 13. The sliding bearing 2 is fixedly installed within the second stepped portion 12, which has a first step with a larger upper diameter and a second step with a smaller lower diameter, and the sliding bearing 2 is press-fitted with the lower second step. The end cap 4 is fixedly installed within the first stepped portion 11. The stepped design of the mounting hole 10, with the diameter decreasing from top to bottom, provides a precise layered installation and positioning structure for the end cap 4, sliding bearing 2, and sealing assembly, ensuring accurate assembly positions and preventing axial misalignment. Furthermore, each component is fixedly installed within its corresponding stepped portion, achieving independent positioning of the components, improving structural stability after assembly, and facilitating disassembly and replacement during subsequent maintenance, thus reducing maintenance costs. Figure 2As shown, the mounting hole 10 also includes a fourth step 14 coaxially disposed below the third step 13; the lower axial end of the fourth step 14 is connected to the upper axial end of the insulation cavity 6, and the diameter of the fourth step 14 is adapted to the outer diameter of the valve stem 5. The fourth step 14 provides additional guiding support for the valve stem 5, further improving the smoothness of the axial sliding of the valve stem 5 and reducing the contact wear between the valve stem 5 and the sealing assembly and the valve stem through hole 7; and the matching of the diameter of the fourth step 14 with the outer diameter of the valve stem 5 can reduce the gap around the valve stem 5, reduce the risk of natural gas leakage, and prevent impurities from entering the insulation cavity 6 or the sealing assembly through the gap, thus playing an auxiliary sealing and protective role.

[0028] like Figure 1 As shown, the sealing assembly includes an annular positioning frame 31 and a sealing ring 32. The positioning frame 31 is sleeved on the valve stem 5, and the sealing ring 32 is sleeved on the positioning frame 31. The outer peripheral wall of the sealing ring 32 abuts against the inner peripheral wall of the mounting hole 10, the inner peripheral wall of the sealing ring 32 abuts against the outer peripheral wall of the positioning frame 31, and the inner peripheral wall of the positioning frame 31 abuts against the outer peripheral wall of the valve stem 5 to achieve a seal. The sealing assembly employs a combination structure of "positioning skeleton 31 + sealing ring 32". The positioning skeleton 31 effectively supports the sealing ring 32, preventing deformation and displacement of the sealing ring 32 during the sliding of the valve stem 5, thus ensuring sealing stability. The sealing ring 32 forms multiple sealing defenses through double contact with the inner circumferential wall of the mounting hole 10 and the outer circumferential wall of the positioning skeleton 31, as well as the contact between the positioning skeleton 31 and the outer circumferential wall of the valve stem 5, significantly improving the sealing effect and effectively preventing natural gas leakage. Furthermore, the contact between the positioning skeleton 31 and the valve stem 5 reduces direct friction between the sealing ring 32 and the valve stem 5, delaying wear of the sealing ring 32 and extending the service life of the sealing assembly. Figure 1 As shown, a concave arc surface 33 is provided circumferentially on the outer peripheral wall of the positioning frame 31. The curvature of the concave arc surface 33 matches the curvature of the inner peripheral wall of the sealing ring 32, and the concave arc surface 33 abuts against the inner peripheral wall of the sealing ring 32. By matching the curvature of the concave arc surface 33 on the outer peripheral wall of the positioning frame 31 with the curvature of the inner peripheral wall of the sealing ring 32 and abutting against it, the contact area between the two is increased, which improves the limiting and fixing effect of the positioning frame 31 on the sealing ring 32 and prevents the sealing ring 32 from slipping or shifting. Furthermore, the fitting structure of the concave arc surface 33 can make the sealing ring 32 more evenly stressed, avoiding damage to the sealing ring 32 caused by local stress concentration. At the same time, it enhances the sealing fit between the sealing ring 32, the positioning frame 31, and the mounting hole 10, further optimizing the sealing performance.

[0029] In this embodiment, the positioning frame 31 is made of PTFE material. PTFE (polytetrafluoroethylene) material has the characteristics of high and low temperature resistance, low coefficient of friction, and chemical corrosion resistance. As the material of the positioning frame 31, it can adapt to the high-temperature working environment of the natural gas EGR valve, reducing frictional wear with the valve stem 5 and the sealing ring 32. Furthermore, the stability of this material ensures that the positioning frame 31 does not deform during long-term use, continuously providing reliable support for the sealing ring 32, ensuring the long-term effectiveness of the sealing structure, and improving the overall durability of the sealing structure. The sealing ring 32 is made of rubber. Rubber material has good elasticity and sealing properties. It can tightly fit the positioning frame 31 and the inner wall of the mounting hole 10 through its own deformation, filling tiny gaps and improving the sealing effect. Furthermore, the elastic properties of rubber material can adapt to the sliding movement of the valve stem 5, reducing frictional damage to the sealing surface, while also possessing certain wear resistance and aging resistance, ensuring the long-term stable operation of the sealing assembly.

[0030] like Figure 1 and Figure 2 As shown, the heat insulation cavity 6 and the valve body 1 are integrally formed. This integral forming reduces assembly gaps, lowers the risk of natural gas leakage, and improves the overall structural strength and stability, preventing the heat insulation cavity 6 from detaching or loosening under high temperature and vibration conditions. The axial cross-section of the heat insulation cavity 6 is an isosceles trapezoid, with the width of the lower base being smaller than the width of the upper base, and the cross-sectional width of the upper base being larger than the cross-sectional width of the sliding bearing 2. The isosceles trapezoidal axial cross-section of the heat insulation cavity 6, with the lower base being narrower than the upper base, optimizes the internal structural layout of the valve body 1 while ensuring sufficient insulation space, reducing material usage and overall weight. Furthermore, the isosceles trapezoidal structure makes the cavity wall of the heat insulation cavity 6 more evenly stressed, improving structural strength and facilitating heat dispersion and transfer, preventing localized high-temperature accumulation, enhancing insulation performance, and better protecting the sealing components and sliding bearing 2 above. By ensuring that the width of the bottom cross section of the heat insulation cavity 6 is greater than the width of the cross section of the sliding bearing 2, sufficient heat insulation space can be formed below the sliding bearing 2, fully covering the corresponding areas of the sliding bearing 2 and the sealing components, improving the comprehensiveness of heat insulation protection, and further delaying the aging of key components.

[0031] Working principle: When high-temperature exhaust gas enters from below the valve stem 5, the trapezoidal structure of the heat insulation chamber 6 effectively disperses and blocks heat from being transferred upwards, protecting the sliding bearing 2 and the sealing assembly above. The sealing assembly is located below the sliding bearing 2, directly facing the direction of exhaust gas flow, and can immediately prevent water vapor, acidic substances, etc. in the exhaust gas from entering the sliding bearing 2 area. When the valve stem 5 moves, the sealing ring 32 maintains a stable shape under the support of the positioning frame 31, ensuring a dynamic sealing effect.

[0032] In summary, the advantages of this invention are: the sealing component is positioned below the sliding bearing 2, and a stepped mounting hole 10 and heat insulation cavity 6 are integrally formed with the valve housing 1. This layout change directly blocks the upward path of water vapor and acidic corrosive substances in the high-temperature exhaust gas, preventing them from corroding and carbonizing the sliding bearing 2, and fundamentally solving the problem of valve stem 5 jamming failure caused by corrosion accumulation. The trapezoidal design of the integrated heat insulation cavity 6 effectively extends the heat conduction path, significantly reduces the heat transfer efficiency to the bearing and sealing area, and enhances high-temperature resistance.

[0033] Structurally, by reducing independent components and optimizing the assembly chain, the tolerance accumulation is significantly shortened, the concentricity and stability of the valve stem 5 movement are improved, and the risk of uneven wear is reduced. The combination of the PTFE positioning skeleton 31 and the rubber sealing ring 32 has the advantages of high temperature resistance, corrosion resistance, self-lubrication, and elastic sealing, further adapting to harsh working conditions.

[0034] The overall solution ensures reliable sealing and efficient heat insulation while achieving structural simplification, convenient assembly, and long service life, providing effective assurance for the reliable operation of the natural gas engine EGR system.

[0035] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0036] In the description of this application, the references to terms such as "an embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0037] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A sealing structure for a natural gas EGR valve, characterized in that, The valve includes a valve housing (1), a sliding bearing (2), a sealing assembly, an end cap (4), and a valve stem (5) arranged coaxially. The valve housing (1) has an axially oriented mounting hole (10). The sliding bearing (2) is disposed within the mounting hole (10). The sealing assembly is disposed within the mounting hole (10) and located axially below the sliding bearing (2). The end cap (4) is disposed within the mounting hole (10) of the valve housing (1) and located axially above the sliding bearing (2), and the end cap (4) closes the opening (101) of the mounting hole (10). The sliding bearing (2) and the sealing assembly are fixed in the mounting hole (10); the valve housing (1) is provided with a heat insulation cavity (6) in a coaxial manner, the upper axial end of the heat insulation cavity (6) is connected to the bottom (102) of the mounting hole (10), and the lower axial end of the heat insulation cavity (6) is provided with a valve stem through hole (7); the valve stem (5) slides through the sliding bearing (2) along the axial direction, and the lower end of the valve stem (5) passes through the end cover (4), the sliding bearing (2), the sealing assembly, the heat insulation cavity (6) and the valve stem through hole (7) from top to bottom.

2. The natural gas EGR valve sealing structure according to claim 1, characterized in that, The mounting hole (10) is stepped and includes a first stepped part (11), a second stepped part (12) and a third stepped part (13) with the hole diameter decreasing sequentially from top to bottom and arranged coaxially; the sealing component is fixedly installed in the third stepped part (13), the sliding bearing (2) is fixedly installed in the second stepped part (12), and the end cap (4) is fixedly installed in the first stepped part (11).

3. The natural gas EGR valve sealing structure according to claim 1, characterized in that, The mounting hole (10) also includes a fourth step (14) coaxially disposed below the third step (13); the lower axial end of the fourth step (14) is connected to the upper axial end of the heat insulation cavity (6), and the diameter of the fourth step (14) is adapted to the outer diameter of the valve stem (5).

4. The natural gas EGR valve sealing structure according to claim 1, characterized in that, The sealing assembly includes an annular positioning frame (31) and a sealing ring (32); the positioning frame (31) is sleeved on the valve stem (5), the sealing ring (32) is sleeved on the positioning frame (31), and the outer peripheral wall of the sealing ring (32) abuts against the inner peripheral wall of the mounting hole (10), the inner peripheral wall of the sealing ring (32) abuts against the outer peripheral wall of the positioning frame (31), and the inner peripheral wall of the positioning frame (31) abuts against the outer peripheral wall of the valve stem (5) to achieve sealing.

5. The natural gas EGR valve sealing structure according to claim 4, characterized in that, The positioning frame (31) has a circular arc concave surface (33) arranged circumferentially on its outer peripheral wall. The curvature of the circular arc concave surface (33) matches the curvature of the inner peripheral wall of the sealing ring (32), and the circular arc concave surface (33) and the inner peripheral wall of the sealing ring (32) are tightly fitted together.

6. The natural gas EGR valve sealing structure according to claim 4, characterized in that, The positioning skeleton (31) is made of PTFE material.

7. The natural gas EGR valve sealing structure according to claim 4, characterized in that, The sealing ring (32) is made of rubber.

8. The natural gas EGR valve sealing structure according to claim 1, characterized in that, The axial cross section of the heat insulation cavity (6) is an isosceles trapezoidal structure, and the width of the lower base of the heat insulation cavity (6) is smaller than the width of the upper base of the heat insulation cavity (6).

9. The natural gas EGR valve sealing structure according to claim 8, characterized in that, The heat insulation cavity (6) and the valve housing (1) are integrally formed, and the cross-sectional width of the bottom of the heat insulation cavity (6) is greater than the cross-sectional width of the sliding bearing (2).

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