Multi-sealing type valve rod sealing structure for EGR (Exhaust Gas Recirculation) lifting valve

Abstract

The multi-sealing type valve rod sealing structure comprises a stainless steel sealing seat, a heat insulation guide cover, a check ring, a first sealing ring and a main sealing piece, the heat insulation guide cover, the check ring, the first sealing ring and the main sealing piece are arranged in the sealing seat from bottom to top, the main sealing piece comprises a second sealing ring, a supporting framework and a third sealing ring, the second sealing ring is a direct sealing link after large-particle impurities are blocked, a waste gas circulation space communicated with a valve body air leakage hole is formed between the second sealing ring and the third sealing ring, waste gas can be exhausted into the atmosphere after entering the waste gas circulation space, and therefore the anti-corrosion function is improved; the heat insulation guide cover can block high temperature caused by waste gas purging and prevent the problem of sealing failure or valve body corrosion caused by the high temperature, so that corrosion of carbon deposition and impurities to the main sealing piece is slowed down through the multi-sealing structure, and the probability of occurrence of valve rod movement hysteresis and sealing failure is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of EGR poppet valves, and in particular to a multi-seal valve stem sealing structure for an EGR poppet valve. Background Art

[0002] The EGR poppet valve is a component used in diesel or gasoline engine emission control systems, mainly used to improve the efficiency of the exhaust gas recirculation (EGR) system. The EGR system guides part of the engine exhaust gas back to the intake port to reduce nitrogen oxides (NO x ) emissions, thereby achieving the purpose of reducing pollution, and the EGR lift valve controls the exhaust gas flow through the up and down movement of the valve stem.

[0003] The stem seal of the EGR poppet valve determines the airtightness of the valve body. Traditional EGR poppet valves use a simple grid ring to achieve sealing through an interference fit with the valve body and stem. This is a structure with upper sealing and lower guiding. However, during the frequent reciprocating movement of the valve stem, due to the poor working environment of the EGR valve, a small amount of carbon deposits and other impurities such as exhaust gas particles will still penetrate between the sealing surfaces and are difficult to clean. This exacerbates the friction between the valve stem, the stem sleeve, and the sealing element, causing wear on parts such as the valve stem, stem sleeve, and grid ring. It can also cause problems such as leakage in the entire valve stem assembly. Especially under high temperatures and the corrosive effects of exhaust gases, abnormal wear and failure are very likely to occur, leading to valve stem sticking and seal failure.

[0004] In order to solve the above problems, technical personnel in the industry proposed adding a sealing seat to the EGR valve stem sealing structure. For details, please refer to the valve stem guide sealing structure of an EGR poppet valve disclosed in Chinese invention patent CN202310007102.5. This scheme provides a sealing seat, in which a retaining frame and two sealing rings are installed. The retaining frame for installing the sealing ring is set in the front position, and the bushing is set above the sealing seat, so as to reduce the entry of dust into the bushing through the two sealing rings on the retaining frame.

[0005] Although the valve stem guide seal structure disclosed in the above patent document reduces the possibility of dust entering the valve stem gap through structural improvement, it still has the following defects in actual application:

[0006] In the above patent document, a scraper is provided below the sealing ring in the sealing seat. Although the scraper can remove large particles of dust attached to the valve stem, it cannot completely prevent small particles of dust from passing through. These small particles of dust can still reach and accumulate near the first sealing ring. Over time, this will cause the first sealing ring to wear and reduce the sealing performance. In addition, the accumulation of dust may also cause valve stem movement hysteresis between the first sealing ring and the valve stem.

[0007] Therefore, although the structural design in the above patent document takes into account the reduction of dust accumulation and the improvement of sealing performance, it still needs to be further optimized to more effectively treat exhaust gas particles to avoid the problems of sealing performance degradation and valve stem response hysteresis that may occur during long-term operation. Utility Model Content

[0008] The present application provides a multi-seal valve stem sealing structure for an EGR poppet valve, so as to solve the problem that the sealing effect of the valve stem sealing structure of the current EGR poppet valve is poor and the valve stem response hysteresis is easily caused.

[0009] In order to achieve the above objectives, this application provides the following technical solutions:

[0010] The present application provides a multi-seal valve stem sealing structure for an EGR lift valve, including an integrated sealing assembly, wherein the integrated sealing assembly includes a sealing seat made of stainless steel and a thermal insulation guide cover, a retaining ring, a secondary seal and a main seal coaxially arranged from bottom to top in a longitudinal through hole in the sealing seat; one end of the thermal insulation guide cover is welded and fixed to the end of the sealing seat, and the thermal insulation guide cover cooperates with the sealing seat to realize the limited installation of the retaining ring; a circle of convex rings is radially provided on the inner wall of the sealing seat, and the bottom of the convex ring and the retaining ring realize the limited installation of the secondary seal, and the secondary seal includes a first sealing ring; the main seal includes a support frame and a second sealing ring and a third sealing ring respectively arranged at the upper and lower ends of the support frame, and the second sealing ring abuts against the top of the convex ring; the first sealing ring, the second sealing ring and the third sealing ring are respectively formed with a central through hole that is interference fit with the outer diameter of the valve stem.

[0011] Furthermore, in the above technical solution, a circle of mounting grooves for mounting the main seal is radially provided on the inner wall of the sealing seat, the mounting groove is located above the convex ring, and a circle of exhaust grooves are radially provided at the position of the mounting groove corresponding to the support frame, and a plurality of exhaust holes are provided at the bottom of the exhaust groove, the exhaust holes are connected with the air leakage holes on the valve body, the exhaust grooves and the support frame form an exhaust gas circulation space between the second sealing ring and the third sealing ring, and when the valve stem moves back and forth up and down, a trace amount of exhaust gas that sneaks into the space between the second sealing ring and the third sealing ring can enter the exhaust gas circulation space and be discharged from the air leakage holes on the valve body.

[0012] Furthermore, the heat-insulating guide cover is a tubular structural part provided at the valve port, a horizontal annular flange for adapting and connecting to the sealing seat is provided at one end of the heat-insulating guide cover, and a guide ring for providing a guide function for the valve stem is provided at the other end, the horizontal annular flange and the guide ring are connected to each other through an intermediate connecting tube, and a chamber is formed between the intermediate connecting tube and the valve stem for blocking high temperature and reducing the upward movement of impurities and carbon deposits in the exhaust gas.

[0013] Furthermore, the intermediate connecting cylinder includes a first vertical cylinder connected to the inner wall of the horizontal annular flange, and a frustum-shaped cylinder connected to the lower end of the first vertical cylinder, and the outer diameter of the frustum-shaped cylinder gradually decreases from the end connected to the first vertical cylinder to the end connected to the guide ring.

[0014] Furthermore, a first mounting hole for mounting the heat insulating guide cover, a second mounting hole for mounting the retaining ring, a third mounting hole for mounting the secondary seal, and a fourth mounting hole for mounting the main seal are formed in sequence from bottom to top in the longitudinal through hole of the sealing seat. The first mounting hole, the second mounting hole and the third mounting hole constitute stepped holes that penetrate each other and have gradually decreasing inner diameters. The top annular surface of the convex ring forms a reduced-diameter transition hole for connecting the third mounting hole and the fourth mounting hole. The horizontal annular flange of the heat insulating guide cover is welded and fixed to the hole wall of the first mounting hole. A central through hole for penetrating and mounting the valve stem is formed on the heat insulating guide cover, the retaining ring, the secondary seal and the main seal. A gap is formed between the guide ring of the heat insulating guide cover, the retaining ring and the convex ring and the valve stem respectively.

[0015] Furthermore, a valve stem sleeve is provided above the integrated sealing assembly. The valve stem sleeve is a hollow cylindrical structure. The inner diameter of the valve stem sleeve is adapted to the outer diameter of the valve stem. The valve stem passes through the valve stem sleeve, the main seal, the secondary seal, the retaining ring and the thermal insulation guide cover from top to bottom.

[0016] Compared with the prior art, this application has at least the following beneficial effects:

[0017] 1. Based on further analysis and research on existing technical problems, the present application recognizes the shortcomings of traditional sealing seats and provides a multi-seal valve stem sealing structure. The integrated sealing component in the multi-seal valve stem sealing structure is an improvement on the basis of the related structure of the traditional sealing seat. The heat-insulating guide cover in the integrated sealing component is welded and fixed to the sealing seat to form a cavity. Such a structural design can effectively prevent impurities and carbon deposits in high-temperature exhaust gas from rising to the sealing seat area, thereby reducing the impact of these impurities on the sealing component, and the heat-insulating guide cover also plays a guiding role to ensure smooth movement of the valve stem; in addition, a retaining ring and a secondary seal (first sealing ring) are provided at one end of the sealing seat connected to the heat-insulating guide cover. The retaining ring can limit the installation of the secondary seal. The secondary seal forms the first sealing barrier behind the heat-insulating guide cover, which can effectively scrape off the carbon deposits attached to the valve stem during the up and down movement of the valve stem. Or small particles of dust, avoid carbon deposits that may be caused by large gaps and large floating from entering the second and third seals at the back, slow down the erosion of the main seal by carbon deposits and impurities, protect the function of the main seal, and ensure the long-term stability of the sealing performance; furthermore, two sealing rings are set on the main seal to form the second and third seals, ensuring that seals are formed at multiple positions to prevent exhaust gas, impurities and other substances from entering the sealing area through the sealing seat. In addition, the stainless steel sealing seat in the present application is corrosion-resistant and separates the valve body from the exhaust gas at the sealing structure, thereby achieving an anti-corrosion effect; therefore, the multi-seal valve stem sealing structure provided in the present application is provided with multiple sealing barriers, so that the main seal can maintain a good sealing state, reduce the phenomenon of valve stem movement hysteresis and sealing failure, thereby effectively improving the response speed of the EGR valve. In addition, good sealing and movement smoothness also help reduce noise caused by friction or imbalance.

[0018] 2. The present application sets multiple seals on the sealing seat, wherein the first seal can effectively scrape off carbon deposits or small particles of dust attached to the valve stem, the second seal is a direct sealing link after blocking large particles of debris, and an exhaust gas circulation space is set between the second and third seals. The exhaust gas circulation space is connected to the gas leakage hole on the valve body. When exhaust gas enters the exhaust gas circulation space, it can be discharged into the atmosphere from the gas leakage hole, thereby improving the anti-corrosion function of the sealing structure; in addition, the gas leakage hole can avoid the accumulation of exhaust gas, thereby preventing the problem of reduced sealing performance or expansion and deformation of the sealing seat due to gas accumulation pressure Occurs; furthermore, after the gas is discharged, the accumulated pressure of the gas can be prevented from causing resistance to the movement of the valve stem, thereby avoiding inflexible operation or sealing failure due to pressure imbalance; in addition, the exhaust gas discharge between the second sealing ring and the third sealing ring can reduce the pressure accumulation between the two, so that the two sealing rings can better perform their sealing functions, and the exhaust gas discharge reduces the external gas pressure on the sealing ring, reduces the deformation and aging rate of the sealing ring, and helps to extend the service life of the sealing ring. Therefore, the structural design of the exhaust gas circulation space and the air bleed hole can also help to maintain the long-term stability of the sealing seat.

[0019] 3. The upper surface of the retaining ring of the present application abuts against the first sealing ring, and the lower surface abuts against the thermal insulation guide cover, thereby ensuring the precise positioning and force distribution of the secondary seal. The retaining ring not only ensures the stability of the position of the secondary seal, but also ensures the overall stability of the sealing structure during the movement of the valve stem through close cooperation with the first sealing ring and the thermal insulation guide cover, so that the secondary seal can better share the pressure and friction generated during the movement of the valve stem, and further reduce the noise and resistance caused by uneven or uneven movement.

[0020] 4. The present application fixes one end of the thermal insulation guide cover to the first mounting hole on the sealing seat by welding. This structural design greatly enhances the connection stability between the thermal insulation guide cover and the sealing seat, improves the deformation resistance of the multi-seal valve stem sealing structure under high temperature and high pressure environments, and improves the mechanical strength and durability of the entire sealing structure. In addition, the thermal insulation guide cover can block the high temperature caused by exhaust gas purge, prevent excessive temperature from causing seal failure, and then corrode the valve body, thereby improving the anti-corrosion function of the structure.

[0021] 5. An isolation chamber is formed between the heat-insulating guide cover and the valve stem of the present application, which can form a physical barrier on the path of exhaust gas flow. It can not only effectively isolate carbon deposits and block high-temperature impurities carried in the exhaust gas, but also protect the seals in the sealing seat from overheating damage in high-temperature environments, thereby improving the heat resistance, sealing and corrosion resistance of the system. In addition, the structure composed of multiple variable-diameter vertical columns can better guide the flow of exhaust gas, effectively reducing the chance of exhaust gas directly contacting the seals, thereby improving the durability of the seals and reducing the risk of sealing failure due to carbon deposit accumulation.

[0022] 6. The present application effectively isolates carbon deposits and blocks high-temperature impurities carried in the exhaust gas through a heat-insulating guide cover, and adopts an integrated sealing assembly to achieve multi-stage sealing of the valve stem. The carbon deposits on the valve stem are scraped off through the first seal, reducing the possibility of dust particles entering the latter two seals, and further preventing the intrusion of tiny particles through the second and third seals. In addition, the trace gas that has entered is discharged through the exhaust gas circulation space between the second and third seals and the air vents on the valve body. Therefore, the present application effectively enhances the sealing performance through structural improvements, reduces the possibility of exhaust gas entering, avoids corrosion of the valve body by exhaust gas, and avoids corrosion of the electric control cabin above the valve stem sleeve after exhaust gas enters the valve stem sleeve, that is, effectively protects the components in the electric control cabin from being corroded by the exhaust gas that has entered, and the overall structure has a strong anti-corrosion function. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, based on the technical concepts and exemplary drawings disclosed in this application, those skilled in the art are able to easily make routine adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, and dimensional ratios of certain units (components).

[0024] Figure 1 This is a schematic cross-sectional view of the integrated sealing assembly of the present application in one embodiment;

[0025] Figure 2 Schematic diagram of the cross-sectional structure of the multi-seal valve stem sealing structure and the valve stem in the installed state provided by the present application in one embodiment.

[0026] Description of reference numerals:

[0027] 1. Sealing seat; 2. Heat insulation guide cover; 3. Retaining ring; 4. Secondary seal; 5. Main seal; 51. Support frame; 52. Secondary sealing ring; 53. Third sealing ring; 6. Valve stem sleeve; 7. Valve stem; 8. Exhaust gas circulation space. DETAILED DESCRIPTION

[0028] The present application will be further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0029] In the description of this application: unless otherwise specified, the meaning of "plurality" is two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0030] Terms such as "upper," "lower," "left," "right," and "center" used in this application are generally intended to facilitate intuitive understanding when compared with the accompanying drawings and are not intended to be absolute limitations on positional relationships in actual products. Changes to these relative positional relationships are considered within the scope of this application without departing from the technical concepts disclosed herein.

[0031] The EGR poppet valve requires frequent reciprocating valve stem movement depending on the vehicle's operating conditions. Due to the large amount of soot in the engine exhaust, this soot forms carbon deposits when it cools. If this carbon deposit enters the gap between the valve stem, the stem sleeve, and the grid ring, it will increase wear or lock the valve stem, causing the EGR poppet valve stem to become stuck or seal ineffective. Furthermore, excessive friction can hinder the high-speed response time of the valve stem's reciprocating motion, leading to increased wear on the valve stem, which can cause the valve stem, stem sleeve, grid ring, and other components to become stuck and locked. This increases friction between the valve stem and the housing during movement, shortening the life of the EGR valve stem and resulting in increased noise during valve stem movement. To avoid these issues, a stem sealing structure is essential for the EGR poppet valve.

[0032] The current valve stem sealing structure for the EGR poppet valve includes a sealing seat and a bushing arranged above the sealing seat. A retainer, two sealing rings and a scraper are installed in the sealing seat. Although such a structure can reduce dust accumulation and improve sealing performance to a certain extent, it still has the following usage defects in actual application: although the scraper can remove large particles of dust attached to the valve stem, it cannot completely prevent small particles of dust from passing through. These small particles of dust can still reach and accumulate near the first sealing ring. Over time, this will cause the first sealing ring to wear and reduce the sealing performance. In addition, the accumulation of dust may also cause valve stem movement hysteresis between the first sealing ring and the valve stem. Therefore, in order to further optimize the valve stem sealing structure to improve its sealing effect and minimize the probability of valve stem response hysteresis or even stuck, the present application provides a multi-seal valve stem sealing structure for an EGR poppet valve.

[0033] This application provides a multi-seal valve stem seal structure for an EGR poppet valve, primarily comprising an integrated seal assembly and a valve stem sleeve 6, which are sleeved onto a valve stem 7. The integrated seal assembly and the valve stem sleeve 6 are sleeved sequentially from bottom to top onto the central portion of the valve stem 7. The integrated seal assembly comprises a stainless steel sealing seat 1 and three sealing structures embedded within the sealing seat 1. Within the sealing seat 1, from bottom to top, are: a thermal insulation guide 2, a retaining ring 3, a first sealing ring, a second sealing ring 52, a support frame 51, and a third sealing ring 53. The structural principles of this multi-seal valve stem seal structure are described in detail below, with reference to the accompanying drawings.

[0034] See also Figure 2 The present application provides a multi-seal valve stem sealing structure for an EGR lift valve, which mainly includes a coaxially arranged integrated sealing component and a valve stem sleeve 6, wherein the valve stem sleeve 6 is arranged above the integrated sealing component.

[0035] See also Figure 1 The integrated sealing assembly includes a sealing seat 1 and a heat-insulating guide cover 2, a retaining ring 3, a secondary seal 4 and a main seal 5 coaxially arranged from bottom to top in a longitudinal through hole in the sealing seat 1, wherein the secondary seal 4 is a first seal ring, and the main seal 5 includes a support frame 51 and a second seal ring 52 and a third seal ring 53 respectively arranged at the upper and lower ends of the support frame 51.

[0036] The longitudinal through hole of the sealing seat 1 is formed from bottom to top with a first mounting hole for mounting the heat-insulating guide cover 2, a second mounting hole for mounting the retaining ring 3, a third mounting hole for mounting the secondary seal 4, and a fourth mounting hole for mounting the main seal 5. In addition, a raised ring is provided radially on the inner wall of the sealing seat 1. The bottom of the raised ring cooperates with the retaining ring 3 to achieve position-limiting mounting of the secondary seal 4, and the top of the raised ring abuts against the second sealing ring 52 for positioning. The first, second, and third mounting holes form stepped holes that are interconnected and have gradually decreasing inner diameters. The top annular surface of the raised ring forms a reduced-diameter transition hole that connects the third and fourth mounting holes. The aforementioned first, second, and third sealing rings 52 and 53 each have a central through hole formed on them that is interference-fit with the outer diameter of the valve stem 7.

[0037] The heat-insulating guide cover 2 in the present application is located at the valve port and is welded to the sealing seat 1 after being pressed and assembled. The internal cavity effectively reduces the impurities and carbon deposits in the exhaust gas from penetrating into the sealing seat 1 while blocking the high-temperature exhaust gas. The secondary seal 4, i.e., the first sealing ring, is located close to the valve port. After it is installed with the retaining ring 3 to limit its position, it forms the first seal, which can scrape off the carbon deposits when the valve stem 7 moves up and down, and avoid the possibility of carbon deposits penetrating into the second and third seals due to large gaps and large floating, and effectively protect the main seal from sealing failure due to the infiltration and corrosion of impurities, effectively ensuring the extension of the service life of the valve stem 7, reducing noise, and shortening the total response time of the EGR valve.

[0038] Continue to see Figure 2 The inner wall of the sealing seat 1 is provided with a circle of mounting grooves for mounting the main seal 5 in the radial direction. The mounting grooves are located above the convex ring. The mounting grooves correspond to the support frame 51 and are provided with a circle of exhaust grooves in the radial direction. The bottom of the exhaust grooves is provided with a number of exhaust holes, which are connected to the bleed holes on the valve body. The exhaust grooves and the support frame form an exhaust gas circulation space 8 between the second sealing ring 52 and the third sealing ring 53. When the valve stem 7 moves back and forth, the trace amount of exhaust gas that sneaks into the space between the second sealing ring 52 and the third sealing ring 53 can enter the exhaust gas circulation space 8 and be discharged from the bleed holes on the valve body. The second seal is the direct sealing link after blocking large particles of debris. The exhaust gas circulation space 8 is provided between the second and third seals. The exhaust gas circulation space 8 is in gas communication with the bleed holes on the valve body. When exhaust gas enters the exhaust gas circulation space 8, it can be discharged into the atmosphere from the bleed holes, thereby improving the anti-corrosion function of the sealing structure.

[0039] The heat-insulating guide cover 2 in this application is a cylindrical structure provided at the valve port. One end of the heat-insulating guide cover 2 is provided with a horizontal annular flange adapted to connect with the sealing seat 1. The horizontal annular flange is welded and fixed to the hole wall of the first mounting hole of the sealing seat 1. The other end is provided with a guide ring for providing guidance for the valve stem 7. The horizontal annular flange and the guide ring are connected through an intermediate connecting tube. A chamber is formed between the intermediate connecting tube and the valve stem 7 to block high temperature and reduce the upward movement of impurities and carbon deposits in the exhaust gas. For details, see Figure 1 The intermediate connecting tube includes a first vertical cylinder connected to the inner wall of the horizontal annular flange and a frustoconical cylinder connected to the lower end of the first vertical cylinder. The outer diameter of the frustoconical cylinder gradually decreases from the end connected to the first vertical cylinder to the end connected to the guide ring. Therefore, an isolation chamber is formed between the heat-insulating guide cover 2 and the valve stem 7 in the present application, which can block the high temperatures caused by exhaust gas purge, prevent excessive temperatures from causing seal failure and subsequent corrosion of the valve body, and enhance the structure's corrosion resistance.

[0040] Continue to see Figure 2The upper surface of the retaining ring 3 abuts the first sealing ring, and the lower surface of the retaining ring 3 abuts the heat-insulating guide cover 2. The inner diameter of the central through-hole of the retaining ring 3 is slightly larger than the outer diameter of the valve stem 7, and the central through-hole of the first sealing ring is connected to the valve stem 7 with an interference fit. This structural design ensures the precise positioning and force distribution of the secondary seal 4. The retaining ring 3 not only ensures the stability of the position of the secondary seal 4, but also, through its close cooperation with the first sealing ring and the heat-insulating guide cover 2, ensures the overall stability of the sealing structure during the movement of the valve stem 7. This allows the secondary seal 4 to better share the pressure and friction generated by the movement of the valve stem 7, further reducing the noise and resistance caused by uneven or uneven movement. In addition, the guide ring of the heat-insulating guide cover 2 and the convex ring on the sealing seat 1 also form gaps with the valve stem 7 respectively, that is, in the multi-seal valve stem sealing structure provided by the present application, only three sealing structures are connected with the valve stem by interference fit to achieve the sealing of the valve stem structure, and a certain gap is formed between the remaining structures and the valve stem to avoid friction during the reciprocating up and down movement of the valve stem to generate flying chips, causing structural wear and affecting the sealing effect.

[0041] The sealing seat 1 of the multi-seal valve stem sealing structure provided in the present application adopts a highly integrated structure and uses multi-layer sealing to protect key components from damage. Through the joint action of the heat-insulating guide cover 2, the retaining ring 3, and the auxiliary seal 4, the sealing seat 1 assembly has the functions of heat insulation, carbon scraping, sealing, and guiding. This sealing structure is superior to the traditional valve stem 7 sealing assembly. The heat-insulating guide cover 2, the retaining ring 3, the auxiliary seal 4, the main seal 5 and the valve stem sleeve 6 in the sealing device are all formed with a central through hole for penetrating and installing the valve stem 7. The structural coaxiality is better, which not only enhances the sealing performance but also helps to reduce the movement resistance of the valve stem 7.

[0042] In summary, this application analyzes the causes of carbon deposits and seal failure on the valve stem, adjusts the position of the assembly parts on the valve stem, moves the sealing seat downward, and adds a secondary seal, namely the first sealing ring, at the end of the sealing seat to effectively scrape off the carbon deposits or small particles of dust attached to the valve stem, effectively improves the working environment of the main seal, reduces the probability of seal failure caused by impurities and carbon deposits in the exhaust gas entering the sealing surface of the valve stem and the sealing ring, and provides a safer sealing environment for the main seal; in addition, two sealing rings are arranged on the main seal to form the second and third seals. The second seal is the direct sealing link after blocking large particles of debris, and an exhaust gas circulation space is set between the second and third seals, and the exhaust gas circulation space is connected to the valve body. The bleed hole is gas-connected, and when exhaust gas enters the exhaust gas circulation space, it can be discharged into the atmosphere from the bleed hole, thereby improving the anti-corrosion function of the sealing structure, avoiding the corrosion of the valve body by the exhaust gas, and avoiding the corrosion of the electric control cabin above the valve stem sleeve after the exhaust gas enters the valve stem sleeve, that is, effectively protecting the components in the electric control cabin from being corroded by the exhaust gas that enters; therefore, the sealing seat in the present application adopts three seals, which provide the valve stem sleeve with an operating environment that is basically free of impurities and exhaust gas through the secondary seal and the main seal, wherein the secondary seal is a single sealing ring structure located near the valve port, which is responsible for blocking larger carbon deposits and other exhaust gas impurities from entering the main seal, and the two sealing rings of the main seal can effectively improve the situation of valve stem movement jamming, reduce the probability of failure, and extend the service life of the product.

[0043] The technical features of the above embodiments can be combined arbitrarily (as long as there is no contradiction in the combination of these technical features). In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

[0044] The present application has been described in a relatively specific and detailed manner through general explanations and specific embodiments. It should be understood that, based on the technical concept of the present application, several conventional adjustments or further innovations may be made to these specific embodiments; however, as long as they do not depart from the technical concept of the present application, the technical solutions obtained by such conventional adjustments or further innovations also fall within the scope of protection of the claims of the present application.

Claims

1. A multi-seal valve stem sealing structure for an EGR poppet valve, characterized in that: The invention comprises an integrated sealing assembly, wherein the integrated sealing assembly comprises a sealing seat (1) made of stainless steel and a heat-insulating guide cover (2), a retaining ring (3), a secondary seal (4) and a main seal (5) coaxially arranged from bottom to top in a longitudinal through hole in the sealing seat (1); one end of the heat-insulating guide cover (2) is welded and fixed to the end of the sealing seat (1); the heat-insulating guide cover (2) cooperates with the sealing seat (1) to realize the limited installation of the retaining ring (3); a convex ring is provided on the inner wall of the sealing seat (1) in the radial direction. The bottom of the convex ring and the retaining ring (3) realize the limited installation of the secondary seal (4), and the secondary seal (4) includes a first sealing ring; the main seal (5) includes a support frame (51) and a second sealing ring (52) and a third sealing ring (53) respectively arranged at the upper and lower ends of the support frame (51), and the second sealing ring (52) abuts against the top of the convex ring; the first sealing ring, the second sealing ring (52) and the third sealing ring (53) are respectively formed with a central through hole that is interference-fitted with the outer diameter of the valve stem.

2. The multi-seal valve stem sealing structure for an EGR poppet valve according to claim 1, characterized in that: A circle of mounting grooves for mounting the main sealing member (5) is radially provided on the inner wall of the sealing seat (1), and the mounting groove is located above the convex ring. A circle of exhaust grooves is radially provided at the position of the mounting groove corresponding to the support frame (51). A plurality of exhaust holes are provided at the bottom of the exhaust groove, and the exhaust holes are connected to the air leakage holes on the valve body. The exhaust groove and the support frame (51) form an exhaust gas circulation space (8) between the second sealing ring (52) and the third sealing ring (53). When the valve stem moves back and forth up and down, a small amount of exhaust gas that penetrates between the second sealing ring (52) and the third sealing ring (53) can enter the exhaust gas circulation space (8) and be discharged from the air leakage holes on the valve body.

3. The multi-seal valve stem sealing structure for an EGR poppet valve according to claim 1 or 2, characterized in that: The heat-insulating guide cover (2) is a cylindrical structural member provided at the valve port. A horizontal annular flange is provided at one end of the heat-insulating guide cover (2) for adapting and connecting with the sealing seat (1), and a guide ring is provided at the other end for providing a guide function for the valve stem. The horizontal annular flange and the guide ring are connected via an intermediate connecting tube. A chamber is formed between the intermediate connecting tube and the valve stem for isolating high temperature and reducing the upward movement of impurities and carbon deposits in the exhaust gas.

4. The multi-seal valve stem sealing structure for an EGR poppet valve according to claim 3, characterized in that: The intermediate connecting cylinder includes a first vertical cylinder connected to the inner wall of the horizontal annular flange, and a frustum-shaped cylinder connected to the lower end of the first vertical cylinder, and the outer diameter of the frustum-shaped cylinder gradually decreases from the end connected to the first vertical cylinder to the end connected to the guide ring.

5. The multi-seal valve stem sealing structure for an EGR poppet valve according to claim 3, characterized in that: The longitudinal through hole of the sealing seat (1) is formed with a first mounting hole for mounting the heat-insulating guide cover (2), a second mounting hole for mounting the retaining ring (3), a third mounting hole for mounting the secondary seal (4), and a fourth mounting hole for mounting the main seal (5) from bottom to top. The first mounting hole, the second mounting hole and the third mounting hole constitute stepped holes that are mutually connected and have gradually reduced inner diameters. The top annular surface of the convex ring forms a reduced diameter transition hole for connecting the third mounting hole and the fourth mounting hole. The horizontal annular flange of the heat-insulating guide cover (2) is welded and fixed to the hole wall of the first mounting hole. The heat-insulating guide cover (2), the retaining ring (3), the secondary seal (4) and the main seal (5) are all formed with a central through hole for penetrating and mounting the valve stem. The guide ring of the heat-insulating guide cover (2), the retaining ring (3) and the convex ring respectively form gaps with the valve stem.

6. The multi-seal valve stem sealing structure for an EGR poppet valve according to claim 1, characterized in that: A valve stem sleeve (6) is provided above the integrated sealing assembly. The valve stem sleeve (6) is a hollow cylindrical structure. The inner diameter of the valve stem sleeve (6) is adapted to the outer diameter of the valve stem. The valve stem passes through the valve stem sleeve (6), the main seal (5), the auxiliary seal (4), the retaining ring (3) and the heat-insulating guide cover (2) in sequence from top to bottom.

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