Low-rotating-speed dry friction mechanical seal and detection method

Abstract

The invention belongs to the field of mechanical seals, and particularly relates to a low-rotating-speed dry friction mechanical seal and a detection method, the rotating speed range is 0.5-200 r / min, the low-rotating-speed dry friction mechanical seal comprises a mandrel, a spring seat, a spring, a moving ring seat, a moving ring, a static ring, a gland and the like, and the mandrel is located in a cavity and can rotate relative to the cavity; the spring seat and the movable ring seat are arranged on the mandrel, the spring seat and the mandrel are completely fixed, and the movable ring seat and the mandrel are fixed in the circumferential direction; the movable ring is arranged on the movable ring seat, and the movable ring and the movable ring seat are processed and fixed into a whole through a special process; the gland is positioned at the outer end of the cavity and is fixedly connected with the cavity through a bolt; the static ring is arranged in the gland and is circumferentially fixed with the gland; the end face of the moving ring and the end face of the static ring are attached to form a sealing face. The sealing effect of the structure is more reliable, and online detection, disassembly and maintenance of the structure are more convenient.

Description

Technical Field

[0001] The invention belongs to the field of mechanical seals, and in particular relates to a low-speed dry friction mechanical seal and a detection method. Background Art

[0002] Dry-running gas seals in the field of mechanical seals are usually achieved by opening flow grooves of various shapes on the surface of the sealing ring, and the sealing end face is mainly composed of three parts: the flow groove, the sealing weir and the sealing dam. The flow groove plays a pumping role, forming a fluid film and generating the fluid film bearing capacity; the sealing weir generates the static and dynamic pressure bearing capacity of the fluid film to prevent leakage in the circumferential direction of the fluid; the sealing dam generates the static pressure bearing capacity of the fluid film to prevent leakage in the radial direction of the fluid.

[0003] After searching, in the prior art, Chinese patent announcement number: CN213899889U, authorization date: 2021-08-16, discloses a dry friction mechanical sealing device, including: a shaft, a sleeve, a flange, a cavity part and a pressure cover, a guide sleeve is provided between the flange and the shaft, a first static ring is provided between the guide sleeve and the flange, the first static ring is axially positioned by a first pressure plate, a second static ring and a throttling ring are provided between the pressure cover and the sleeve, a driving ring is provided on one side of the second pressure plate, a first dynamic ring, a second dynamic ring and a shape strip are provided between the cavity part and the sleeve, the pressure cover is provided with a leakage guide and flushing channel, the pressure cover, the second dynamic ring, the second static ring, the first dynamic ring, the first static ring, the first pressure plate and the cavity part are together surrounded to form a sealed cavity, an isolation gas is provided in the sealed cavity, the pressure of the isolation gas is greater than the pressure of the sealed gas, and the cavity part is provided with an isolation gas inlet channel and an isolation gas outlet channel which are connected with the sealing cavity, thereby greatly improving its sealing performance.

[0004] Although the above embodiments can prevent the sealed gas from leaking out and causing accidents. However, dry-running gas seals are often used in equipment with higher rotation speeds, such as compressors. When the rotation speed is low and the fluid film is difficult to form, their applicability is low. The mechanical seals used in the upper stirring kettles in the pharmaceutical and food industries usually rotate at a speed of 20-200r / min. The stirring kettle needs to be sealed to prevent leakage. In addition, the rotation speed of the mechanical penetrations of the personnel gates of nuclear power plants is also relatively low. The mechanical seal rotation speed of the mechanical penetrations of the personnel gates is 0.5-200r / min. This kind of mechanical seal structure that maintains good sealing performance under low-speed dry friction conditions is also required. At this time, a mechanical seal suitable for dry friction conditions is needed. The mechanical seal needs to maintain a good friction pair end face state under dry friction conditions, provide stable and reliable sealing performance, and ensure the safety of the personnel gate equipment of nuclear power plants. Summary of the invention

[0005] The purpose of the present invention is to provide a low-speed dry friction mechanical seal, which can achieve effective sealing in the speed range of 0.5-200r / min and the state of dry friction of the end face contact, so as to improve the sealing performance and service life of the equipment.

[0006] In view of the above problems, the present invention provides a low-speed dry friction mechanical seal and detection method, including a core shaft, a spring seat, a dynamic ring seat, a dynamic ring, a pressure cover, a static ring, and a spring; the core shaft is located in a cavity, the core shaft and the cavity are relatively fixed in the axial direction and can rotate circumferentially; the spring seat and the dynamic ring seat are arranged on the core shaft, the spring seat is completely fixed to the core shaft, and the dynamic ring seat and the core shaft are circumferentially fixed; the dynamic ring is arranged on the dynamic ring seat, and is circumferentially and axially fixed to the dynamic ring seat; the pressure cover is located at the outer end of the cavity, and is fixedly connected to the cavity by bolts; the static ring is arranged in the pressure cover, and is circumferentially fixed to the pressure cover.

[0007] Preferably, the spring seat is in contact with the shoulder of the core shaft, a threaded through hole is machined on the spring seat, a set screw is arranged in the hole, and complete fixation with the core shaft is achieved through the set screw.

[0008] Preferably, the end of the spring seat away from the core shaft shoulder is processed with a plurality of countersunk holes with flat bottoms, and a plurality of springs are arranged in the holes, and the two ends of the springs respectively press against the bottom of the countersunk holes of the spring seat and the end surface of the moving ring seat away from the moving ring.

[0009] Preferably, two shaft sealing rings are arranged between the moving ring seat and the core shaft. The shaft sealing rings are installed in the sealing ring groove of the moving ring seat and are pressed by the core shaft. A cylindrical pin is arranged between the moving ring seat and the core shaft. The cylindrical pin is arranged on the core shaft and cooperates with the groove of the moving ring seat to keep the core shaft and the moving ring seat circumferentially fixed.

[0010] Preferably, the moving ring seat and the moving ring are fixed as one body, and the moving ring and the moving ring seat are kept circumferentially fixed through the fixed connection between the moving ring and the moving ring seat, and the side of the moving ring away from the moving ring seat is fit with the side of the static ring away from the pressure cover through the spring seat, so as to achieve the effect of end face sealing.

[0011] Preferably, two stationary ring sealing rings are arranged between the stationary ring and the gland, and the stationary ring sealing rings are installed in the sealing ring grooves of the gland and are compressed by the stationary ring.

[0012] Preferably, a through hole is processed between the sealing ring grooves of the two static ring sealing rings of the gland and is connected with the threaded detection hole of the gland as the first leakage detection channel; axial and radial blind holes are processed inside the static ring as the second leakage detection channel, the axial hole is concentric with the through hole on the dynamic ring, and the radial hole is concentric with the leakage detection channel hole of the gland.

[0013] Preferably, a gland sealing ring is provided between the gland and the cavity, the gland sealing ring is installed in a sealing ring groove of the gland, and the gland is pressed against the cavity by bolts.

[0014] The present invention provides a method for detecting a low-speed dry friction mechanical seal, comprising the following steps:

[0015] S1. Connect and install the air tightness detection equipment to the threaded detection hole on the gland, and set relevant parameters of the air tightness detection equipment;

[0016] S2, injecting gas into the first leakage detection channel, after the gas fills the second leakage detection channel, thereby detecting the sealing performance of the gland and the static ring through the static ring sealing ring;

[0017] S3. Continue to inject gas into the first leakage detection channel. After the gas pushes the static ring and the dynamic ring apart, it enters the third leakage detection channel, thereby detecting the sealing between the dynamic ring and the static ring and the sealing between the core shaft and the dynamic ring seat.

[0018] The beneficial effects of the present invention are:

[0019] 1. The dynamic ring seal end face in the low-speed dry friction mechanical seal and detection method provided by the present invention is integrally fixedly connected with the dynamic ring seat. This structure has the characteristics of excellent sealing effect, high reliability, long service life, etc.

[0020] 2. The leakage detection channel in the low-speed dry friction mechanical seal and detection method provided by the present invention is conducive to online detection of the sealing performance of the mechanical seal, without the need to dismantle the mechanical seal as a whole to detect the sealing performance;

[0021] 3. A low-speed dry friction mechanical seal and detection method provided by the present invention adopts a structure of multiple small springs, so that the dynamic seal assembly is more evenly stressed as a whole, which is conducive to maintaining a good fit state of the sealing end face, improving the stability of the mechanical seal, and extending the service life of the mechanical seal;

[0022] 4. The low-speed dry friction mechanical seal and detection method provided by the present invention has a simple disassembly and assembly process and is convenient for maintenance and replacement.

[0023] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the structure of an embodiment of the present invention is shown;

[0026] Figure 2 A schematic cross-sectional view of a mandrel according to an embodiment of the present invention is shown;

[0027] Figure 3 A schematic cross-sectional view of a dynamic ring seat according to an embodiment of the present invention is shown;

[0028] Figure 4 A schematic diagram of the structure at location A according to an embodiment of the present invention is shown.

[0029] In the figure: 1. cavity; 2. spring seat; 3. set screw; 4. cylindrical pin; 5. dynamic ring seat; 7. dynamic ring; 8. static ring; 9. anti-rotation pin; 10. gland; 11. bolt; 12. static ring seal; 13. gland seal; 14. first dynamic ring seal; 15. shaft seal; 16. second dynamic ring seal; 17. spring; 18. core shaft. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] like Figures 1 to 4As shown, a low-speed dry friction mechanical seal provided by the present invention comprises a core shaft 18, a spring seat 2, a dynamic ring seat 5, a dynamic ring 7, a pressure cover 10, a static ring 8, a spring 17, etc.; the core shaft 18 is located in the cavity 1, and the core shaft 18 is relatively fixed to the cavity 1 in the axial direction and can rotate circumferentially; the spring seat 2 and the dynamic ring seat 5 are arranged on the core shaft 18, the spring seat 2 is completely fixed to the core shaft 18, and the dynamic ring seat 5 is circumferentially fixed to the core shaft 18; the dynamic ring 7 is arranged on the dynamic ring seat 5, and is circumferentially and axially fixed to the dynamic ring seat 5, and the two parts are fixed together by an integral connection, which can be specifically bonded, etc., and the two parts are completely fixed, so as to reduce the failure of the matching caused by the setting of the positioning pin and the sealing ring and the failure caused by the vibration and friction during use; the pressure cover 10 is located at the outer end of the cavity 1, and is fixedly connected to the cavity 1 by bolts 11; the static ring 8 is arranged in the pressure cover 10, and is circumferentially fixed to the pressure cover 10; the dynamic ring 7 contacts the end face of the static ring 8 to achieve the effect of end face sealing.

[0033] Furthermore, the spring seat 2 is in contact with the shoulder of the core shaft 18, and a threaded through hole is processed on the spring seat 2, and a set screw 3 is arranged in the hole, and the spring seat 2 is completely fixed to the core shaft 18 through the set screw 3; the end of the spring seat 2 away from the shoulder of the core shaft 18 is processed with a plurality of countersunk holes with flat bottoms, and a plurality of springs 17 are arranged in the hole; the two ends of the spring 17 respectively press against the bottom of the countersunk hole of the spring seat 2 and the side of the moving ring seat 5 away from the moving ring 7, so as to provide a stable spring 17 force for the contact end surface of the moving ring 7 and the static ring 8, so that the moving ring 7 has a certain compensation ability after wear.

[0034] Furthermore, two shaft sealing rings 15 are arranged between the moving ring seat 5 and the core shaft 18. The shaft sealing rings 15 are installed in the sealing ring groove of the moving ring seat 5 and are pressed by the core shaft 18 to form a sealing point; a cylindrical pin 4 is arranged between the moving ring seat 5 and the core shaft 18. The cylindrical pin 4 is arranged on the core shaft 18 and cooperates with the anti-rotation pin 9 groove of the moving ring seat 5, so that the core shaft 18 and the moving ring seat 5 are kept circumferentially fixed; a first moving ring sealing ring 14 and a second moving ring sealing ring 16 are arranged between the moving ring seat 5 and the moving ring 7 and are installed in the sealing ring groove of the moving ring seat 5 and are pressed by the moving ring 7 to form a sealing point; two anti-rotation pins 9 are arranged between the moving ring seat 5 and the moving ring 7. The anti-rotation pin 9 is arranged on the moving ring seat 5 and cooperates with two pin holes on the end face of the moving ring 7 away from the static ring 8, so that the moving ring 7 and the moving ring seat 5 are kept circumferentially fixed.

[0035] Furthermore, an annular groove is machined between the sealing ring grooves of the two shaft sealing rings 15 of the dynamic ring seat 5, and a through hole is machined between the sealing ring grooves of the first dynamic ring sealing ring 14 and the second dynamic ring sealing ring 16 and connected to the annular groove as a leakage detection channel.

[0036] Furthermore, a circular groove is processed on the end face of the moving ring 7 away from the moving ring seat 5 to form a radial double-end face structure. A through hole is processed in the groove, and the hole position is concentric with the through hole on the moving ring seat 5 to serve as a leakage detection channel.

[0037] Furthermore, two stationary ring sealing rings 12 are arranged between the stationary ring 8 and the pressure cover 10. The stationary ring sealing rings 12 are installed in the sealing ring groove of the pressure cover 10 and are compressed by the stationary ring 8 to form a sealing point; the anti-rotation pin 9 is installed on the pressure cover 10 and cooperates with the notch of the stationary ring 8 at one end away from the dynamic ring 7, so that the stationary ring 8 and the pressure cover 10 remain circumferentially fixed.

[0038] Furthermore, a through hole is processed between the sealing ring grooves of the two static ring sealing rings 12 of the gland 10 and is connected with the threaded detection hole of the gland 10 as a first leakage detection channel.

[0039] Furthermore, axial and radial blind holes are processed inside the static ring 8 as a second leakage detection channel. The axial hole is concentric with the through hole on the dynamic ring 7 , and the radial hole is concentric with the leakage detection channel hole of the gland 10 .

[0040] Furthermore, a gland sealing ring 13 is provided between the gland 10 and the cavity 1. The gland sealing ring 13 is installed in the sealing ring groove of the gland 10. The gland 10 is pressed against the cavity 1 by bolts 11 to form a sealing point.

[0041] The present invention provides a method for detecting a low-speed dry friction mechanical seal, comprising the following steps:

[0042] S1. Connect and install the airtightness detection device to the threaded detection hole on the gland 10, and set the relevant parameters of the airtightness detection device;

[0043] In this step, the air tightness testing equipment may specifically be composed of an air compressor, an air storage tank, and corresponding instruments and valves. The air pressure value of the mechanical seal is set according to the testing procedure, so as to perform online testing on the sealing performance of the mechanical seal.

[0044] S2, by injecting gas into the first leakage detection channel, after the gas fills the second leakage detection channel, the gland 10 and the static ring 8 are tested, and the sealing performance of the static ring seal 12 is tested;

[0045] In this step, there are two situations at the outlet end of the second leakage detection channel. When the second leakage detection channel is directly aligned with and connected to the third leakage detection channel, the gas will directly fill the third leakage detection channel. After filling the third leakage detection channel, the air tightness test between the static ring 8 and the pressure cover 10 will be completed; when the second leakage detection channel is not aligned with the third leakage detection channel, the outer section of the dynamic ring 7 will block the second leakage detection channel, thereby completing the air tightness test between the static ring 8 and the pressure cover 10.

[0046] S3. Continue to inject gas into the first leakage detection channel. After the gas pushes the static ring 8 and the dynamic ring 7 apart, it enters the third leakage detection channel, thereby detecting the sealing between the dynamic ring 7 and the static ring 8 and the sealing between the detection core shaft 18 and the dynamic ring seat 5.

[0047] In this step, when the second leakage detection channel is directly aligned and connected with the third leakage detection channel, the gas will first separate the static ring 8 and the dynamic ring 7, thereby partially filling the cavity, and then detect the core shaft 18; when the second leakage detection channel is not aligned with the third leakage detection channel, the gas will first push open the dynamic ring 7 and the static ring 8, then fill the cavity with gas, and finally fill the third leakage channel to detect the air tightness of the core shaft 18.

[0048] A method for detecting a low-speed dry friction mechanical seal is proposed by an embodiment of the present invention, and its working principle is as follows:

[0049] The integrated fixation of the dynamic ring 7 and the dynamic ring seat 5 further improves the overall reliability of the equipment; the mutual cooperation of the first leakage detection channel, the second leakage detection channel and the third leakage detection channel forms an online detection structure that is conducive to the sealing performance detection of the mechanical seal, and there is no need to dismantle the mechanical seal as a whole for detection, thereby improving the convenience of the structure; by installing multiple springs 17, the force between the structures is made more uniform and stable, which can effectively reduce the influence of factors such as vibration, deflection and eccentricity, so that the contact of the sealing end face is in good condition, and the end face can be kept in good wear condition, thereby extending the service life and stability of the mechanical seal; both the dynamic ring 7 and the static ring 8 are detachable, the disassembly and assembly process is simple, and maintenance and replacement work is convenient.

[0050] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-speed dry friction mechanical seal, comprising a core shaft (18), a spring seat (2), a dynamic ring seat (5), a dynamic ring (7), a gland (10), a static ring (8), and a spring (17), characterized in that: The core shaft (18) is located in the cavity (1), and the core shaft (18) and the cavity (1) are relatively fixed in the axial direction and can rotate in the circumferential direction; The spring seat (2) and the dynamic ring seat (5) are arranged on the core shaft (18), and the spring seat (2) and the core shaft (18) are completely fixed, and the dynamic ring seat (5) and the core shaft (18) are kept fixed in the circumferential direction; The dynamic ring (7) is arranged on the dynamic ring seat (5), and the dynamic ring (7) and the dynamic ring seat (5) are fixedly connected and mutually locked in the radial direction and the axial direction; The gland (10) is located at the outer end of the cavity (1) and is fixedly connected to the cavity (1); The stationary ring (8) is arranged in the gland (10) and is circumferentially fixed to the gland (10).

2. The low speed dry friction mechanical seal according to claim 1, characterized in that: The spring seat (2) contacts the shaft shoulder of the core shaft (18); a threaded hole is machined on the spring seat (2); a set screw (3) is arranged in the threaded hole; the spring seat and the core shaft (18) are fixed by the set screw (3).

3. The low speed dry friction mechanical seal according to claim 2, characterized in that: A plurality of countersunk holes with flat bottoms are machined at one end of the spring seat (2) away from the shaft shoulder of the core shaft (18), and a plurality of springs (17) are arranged in the countersunk holes. The two ends of the springs (17) respectively abut against the bottom of the countersunk holes and a side of the movable ring seat (5) away from the movable ring (7).

4. The low speed dry friction mechanical seal according to claim 3, characterized in that: Two shaft sealing rings (15) are arranged between the moving ring seat (5) and the core shaft (18). The shaft sealing ring (15) is installed in the first sealing ring groove of the moving ring seat (5) and is pressed by the core shaft (18). A cylindrical pin (4) is arranged between the moving ring seat (5) and the core shaft (18). The cylindrical pin (4) is arranged on the core shaft (18), and the cylindrical pin (4) cooperates with the notch of the sealing ring groove, so that the core shaft (18) and the moving ring seat (5) are kept circumferentially fixed.

5. The low speed dry friction mechanical seal according to claim 4, characterized in that: By radially locking the moving ring (7) and the moving ring seat (5), the moving ring (7) and the moving ring seat (5) are kept circumferentially fixed, and a side of the moving ring (7) away from the moving ring seat (5) is in contact with a side of the stationary ring (8) away from the gland (10), thereby achieving an end face sealing effect.

6. The low speed dry friction mechanical seal according to claim 5, characterized in that: Two stationary ring sealing rings (12) are arranged between the stationary ring (8) and the gland (10); the stationary ring sealing rings (12) are installed in the second sealing ring groove of the gland (10) and are compressed by the stationary ring (8).

7. The low speed dry friction mechanical seal according to claim 6, characterized in that: A first through hole is machined between the second sealing ring grooves of the two stationary ring sealing rings (12) of the pressure cover (10), and the first through hole is connected with the threaded detection hole provided on the pressure cover (10) to serve as a first leakage detection channel; an axial blind hole and a radial blind hole are machined inside the stationary ring (8), and the axial blind hole is connected with the radial blind hole to serve as a second leakage detection channel; an annular groove and a second through hole for detection are provided between the moving ring (7) and the moving ring seat (5), and the annular groove and the second through hole serve as a third leakage detection channel, and the axial blind hole is concentric with the third leakage detection channel, and the radial blind hole is concentric with the first leakage detection channel.

8. The low speed dry friction mechanical seal according to claim 7, characterized in that: A gland sealing ring (13) is provided between the gland (10) and the cavity (1); the gland sealing ring (13) is installed in the second sealing ring groove of the gland (10); and the gland (10) is pressed tightly against the cavity (1).

9. The low speed dry friction mechanical seal according to claim 8, characterized in that: The speed range of mechanical seal is 0.5-200r / min.

10. A detection method for a low-speed dry friction mechanical seal according to claim 8, characterized in that: The following steps are involved: S1. Connecting and installing an airtightness detection device to the threaded detection hole on the gland (10), and setting relevant parameters of the airtightness detection device; S2, injecting gas into the first leakage detection channel, after the gas fills the second leakage detection channel, thereby detecting the sealing performance of the gland (10) and the static ring (8) sealed by the static ring sealing ring (12); S3. Continue to inject gas into the first leakage detection channel. After the gas pushes the static ring (8) and the dynamic ring (7) apart, it enters the third leakage detection channel, thereby detecting the sealing between the dynamic ring (7) and the static ring (8) and detecting the sealing between the core shaft (18) 18 and the dynamic ring seat (5).

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