Mechanical seal for screw pump
By using a floating static ring installation and a flexible connection design, the high cost and easy failure of mechanical seals for screw pumps under harsh operating conditions are solved, achieving low-cost and high-efficiency sealing performance and ensuring synchronous rotation and sealing effect of the static and dynamic rings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NINGBO VULCAN TECH CO LTD
- Filing Date
- 2025-09-23
- Publication Date
- 2026-07-21
AI Technical Summary
Existing mechanical seals for screw pumps are costly and prone to failure under harsh operating conditions, especially after long-term shutdowns when a shiny band appears on the sealing end face, affecting sealing performance.
The stationary ring adopts a floating installation structure, combining axial and radial floating design. The stationary ring and stationary ring seat are softly connected by a pin connection and a PTFE ring washer. The rotating ring assembly provides synchronous rotational force through a wave spring, which enhances the sealing effect.
It reduces the cost of the stationary ring assembly, improves sealing performance, ensures synchronous rotation and sealing effect of the stationary and rotating rings, avoids failure problems caused by hard connections, and provides radial and axial floating space.
Smart Images
Figure CN224532969U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of mechanical seal technology, specifically a mechanical seal for a screw pump. Background Technology
[0002] Mechanical seals are shaft sealing devices used in rotating fluid machinery (such as pumps, compressors, agitators, etc.), also known as end face seals. Their main function is to prevent fluid leakage inside the equipment while preventing the ingress of external air or impurities. Due to their advantages such as low leakage, long service life, and low power consumption, they have been widely used in various industrial fields, largely replacing traditional soft packing seals.
[0003] Mechanical seals generally consist of a stationary ring assembly and a rotating ring assembly. The stationary ring assembly comprises a sealing stationary ring and a stationary ring seat. Currently, one type of stationary ring uses an alloy structure, applied under harsh operating conditions, such as nickel-based, cobalt-based, and chromium-based hard alloys, due to their excellent overall performance. Existing technologies use integral alloy stationary rings, but the significant increase in alloy material costs increases the cost of the stationary ring, hindering sales. There have also been attempts at using an insert structure, where an alloy-material stationary ring is installed in a stationary ring seat made of a non-alloy material. This structure can develop fractures due to internal stress, leading to mechanical seal failure and rendering the seal unusable. Especially when the pump has been shut down for a long time without being restarted, a shiny band may appear on the sealing end face upon restarting; this is an uncontrollable process. Utility Model Content
[0004] The technical problem to be solved by this utility model is to provide a mechanical seal for screw pumps that allows the stationary ring to float inside the stationary ring seat, thereby reducing costs and allowing the stationary ring to have a certain floating space in the radial and axial directions, thus improving sealing performance.
[0005] The technical solution of this utility model is to provide a mechanical seal for a screw pump with the following structure: a rotating shaft passing through a pump cover, a stationary ring assembly, a rotating ring assembly, an elastic assembly, and a drive ring; an annular cavity is provided between the outer wall of the rotating shaft and the inner wall of the pump cover; the stationary ring assembly, rotating ring assembly, elastic assembly, and drive ring are all sleeved on the outside of the rotating shaft and located in the annular cavity; the stationary ring assembly includes a stationary ring and a stationary ring seat, and the stationary ring seat is located in the first stepped hole of the pump cover; the stationary ring is floatingly connected in the second stepped hole of the stationary ring seat and connected by an axially arranged first pin. A gap is provided between the outer wall of the stationary ring and the inner wall of the stepped hole of the stationary ring seat, and a gap is provided between the inner wall of the stationary ring and the outer wall of the rotating shaft. The sealing end face of the stationary ring extends out of the stationary ring seat and is in close contact with the rotating ring of the rotating ring assembly. A first annular groove is provided on the inner wall of the second stepped hole of the stationary ring seat, and a first sealing ring is provided in the first annular groove. The first sealing ring abuts against the bottom surface of the first annular groove and the outer wall of the stationary ring, so that the stationary ring and the stationary ring seat are softly connected in the radial direction. In addition, the inner end face of the stationary ring and the stepped surface of the second stepped hole of the stationary ring seat are connected in the axial direction by a soft connection structure.
[0006] The moving ring assembly also includes a moving ring seat, wherein the moving ring is disposed in the third stepped hole at one end of the moving ring seat and rotates synchronously with the moving ring seat through a second pin.
[0007] The elastic component is at least one set of wave springs, the wave springs are located at the tail of the moving ring seat, and the tail of the moving ring seat is provided with a retaining ring; the tail of the driving ring is fixed on the rotating shaft, and the front end of the driving ring extends to the outer wall of the moving ring seat and both are provided with a second circumferential positioning structure for synchronous rotation of both; one end of the wave spring abuts against the retaining ring, and the other end abuts against the stepped surface of the central hole of the driving ring, thereby pushing the moving ring and the stationary ring to fit tightly together.
[0008] The inner end of the stationary ring is provided with multiple positioning holes, and the end face of the stepped hole of the stationary ring seat is provided with first pins in the same position and number as the positioning holes. The first pins are embedded into the corresponding positioning holes one by one, and the stationary ring and the stationary ring seat are circumferentially positioned.
[0009] The inner wall of the central hole of the moving ring seat is provided with a second annular groove, and a second sealing ring is provided in the second annular groove. The inner wall of the second sealing ring is tightly sealed to the moving ring.
[0010] The axial soft connection structure between the inner end face of the stationary ring and the stepped surface of the second stepped hole of the stationary ring seat means that a PTFE annular washer is provided in the second stepped hole of the stationary ring seat, and the PTFE annular washer abuts between the stepped surface of the second stepped hole and the inner end face of the stationary ring, thereby making the inner end face of the stationary ring and the stationary ring seat softly connected; the PTFE annular washer has a notch for the first pin to pass through.
[0011] With the above structure, this utility model has the following advantages: 1. The stationary ring is floatingly connected in the second stepped hole of the stationary ring seat and connected by an axially set first pin, thereby realizing a circumferential positioning structure between the stationary ring and the stationary ring seat in the floating installation structure, ensuring that neither rotates. 2. There is a gap between the outer wall of the stationary ring and the inner wall of the stepped hole of the stationary ring seat, and there is a gap between the inner wall of the stationary ring and the outer wall of the rotating shaft, providing the stationary ring with radial and axial floating space, avoiding hard connection between the two. 3. The sealing end face of the stationary ring extends out of the stationary ring seat and is in close contact with the rotating ring of the rotating ring assembly; the inner wall of the second stepped hole of the stationary ring seat is provided with a first annular groove, and a first sealing ring is provided in the first annular groove. The first sealing ring abuts against the bottom surface of the first annular groove and the outer wall of the stationary ring, respectively, so that the stationary ring and the stationary ring seat are softly connected in the radial direction; this radial soft structure connection not only realizes the soft connection, but also achieves the sealing between the outer wall of the stationary ring and the inner wall of the stationary ring seat, and at the same time, the structure is simple and has good reliability. 4. In addition, the inner end face of the stationary ring and the stepped surface of the second stepped hole of the stationary ring seat are connected in the axial direction by a soft connection structure. The axial soft connection structure is installed on the inner end face of the stationary ring, so as not to affect the radial floating of the stationary ring.
[0012] As an improvement, the moving ring assembly also includes a moving ring seat 10. One end of the moving ring seat 10 is provided with a third step hole 11. The moving ring 8 is disposed in the third step hole 11 and connected by a second pin 20 to achieve circumferential positioning and synchronous rotation. The pin connection provides good circumferential positioning and can ensure that the two rotate synchronously.
[0013] As an improvement, the elastic component is at least one set of wave springs located at the tail of the rotating ring seat, and the tail of the rotating ring seat is provided with a retaining ring; the tail of the driving ring is fixed on the rotating shaft, and the front end of the driving ring extends to the outer wall of the rotating ring seat, and both are provided with a second circumferential positioning structure for synchronous rotation of both; one end of the wave spring abuts against the retaining ring, and the other end abuts against the stepped surface of the center hole of the driving ring, thereby pushing the rotating ring and the stationary ring to fit tightly together. The wave spring structure of this type saves the axial space of the entire mechanical seal, and also provides a uniform thrust to the rotating ring.
[0014] As an improvement, the inner end of the stationary ring is provided with multiple positioning holes, and the end face of the stepped hole of the stationary ring seat is provided with first pins in the same position and number as the positioning holes. The first pins are embedded into the corresponding positioning holes one by one, and the stationary ring and the stationary ring seat are circumferentially positioned. The pin connection provides good circumferential positioning effect and can ensure that the two rotate synchronously.
[0015] As an improvement, the inner wall of the central hole of the moving ring seat is provided with a second annular groove, and a second sealing ring is provided in the second annular groove. The inner wall of the second sealing ring is tightly attached to the moving ring for sealing, so that the outer wall of the moving ring can also have a certain radial movement gap while sealing.
[0016] As an improvement, the axial soft connection structure between the inner end face of the stationary ring and the stepped surface of the second stepped hole of the stationary ring seat means that a PTFE annular washer is provided in the second stepped hole of the stationary ring seat. The PTFE annular washer abuts against the stepped surface of the second stepped hole and the inner end face of the stationary ring, thereby making the inner end face of the stationary ring and the stationary ring seat a soft connection. The PTFE annular washer has a notch for the first pin to pass through. The PTFE annular washer can add another sealing structure to the stationary ring, giving the stationary ring a double seal and improving the sealing effect. Attached Figure Description
[0017] Figure 1 This is a cross-sectional schematic diagram of the mechanical seal for the screw pump of this utility model.
[0018] Figure 2 This is a cross-sectional schematic diagram of the stationary ring assembly of this utility model.
[0019] Figure 3 for Figure 2 Enlarged schematic diagram of part A.
[0020] Figure 4 This is a cross-sectional schematic diagram of the dynamic ring assembly of this utility model.
[0021] Figure 5 for Figure 4 Enlarged schematic diagram of part B.
[0022] Figure 6 This is a three-dimensional schematic diagram of the mechanical seal for a screw pump according to the present invention.
[0023] Figure 7 This is a three-dimensional schematic diagram of the stationary ring assembly of this utility model.
[0024] Figure 8 This is a schematic diagram of the exploded body of the stationary ring assembly of this utility model.
[0025] As shown in the figure:
[0026] 1. Pump cover, 2. Rotary shaft, 3. Drive ring, 4. Stationary ring, 5. Stationary ring seat, 6. First pin, 7. Second stepped hole, 8. Moving ring, 9. First annular groove, 10. Moving ring seat, 11. Third stepped hole, 12. Wave spring, 13. Retaining ring, 14. Stepped surface, 15. Positioning hole, 16. Second annular groove, 17. Second sealing ring, 18. First sealing ring, 19. PTFE annular gasket. Detailed Implementation
[0027] The present invention will be further described below with reference to the accompanying drawings.
[0028] like Figure 1-8As shown, the mechanical seal for a screw pump of this utility model includes a rotating shaft 2 passing through a pump cover 1, a stationary ring assembly, a rotating ring assembly, an elastic assembly, and a drive ring 3. An annular cavity is provided between the outer wall of the rotating shaft 1 and the inner wall of the pump cover 1. The stationary ring assembly, rotating ring assembly, elastic assembly, and drive ring 3 are all sleeved on the outside of the rotating shaft 1 and located in the annular cavity. The sealing end face of the stationary ring 4 of the stationary ring assembly extends out of the stationary ring seat 5 and is in close contact with the rotating ring 8 of the rotating ring assembly.
[0029] like Figure 2 and Figure 3 As shown, the stationary ring assembly includes a stationary ring 4 and a stationary ring seat 5. The stationary ring seat 5 is located in the first stepped hole of the pump cover 1. The stationary ring 4 is floatingly connected in the second stepped hole 7 of the stationary ring seat 5 and is connected by an axially arranged first pin 6. In this embodiment, there are four rings, which are evenly distributed and spaced 90 degrees apart.
[0030] like Figure 3 , Figure 6 and Figure 7 As shown, there is a gap between the outer wall of the stationary ring 4 and the inner wall of the stepped hole of the stationary ring seat 5, and a gap between the inner wall of the stationary ring 4 and the outer wall of the rotating shaft 2. These two gaps provide a floating distance between the stationary ring 4 and the stationary ring seat 5, meaning that the stationary ring 4 can move radially outward or radially inward with a certain amount of space. This allows the stationary ring to automatically follow the rotating ring (moving ring) for slight radial adjustments under the elastic support of the sealing ring, ensuring that the stationary ring and the moving ring always maintain good fit and parallelism.
[0031] like Figure 3 and Figure 8 As shown, the inner wall of the second stepped hole 7 of the stationary ring seat 5 is provided with a first annular groove 9, which is located at the middle position of the outer wall of the stationary ring 4. A first sealing ring 18 is provided in the first annular groove 9, which abuts against the bottom surface of the first annular groove 9 and the outer wall of the stationary ring 4, so that the stationary ring 4 and the stationary ring seat 5 are softly connected in the radial direction.
[0032] The inner end of the stationary ring 4 is provided with a plurality of positioning holes 15. The end face of the stepped hole of the stationary ring seat 5 is provided with a first pin 6 in the same position and number as the positioning holes 15. The first pin 6 is embedded into the corresponding positioning hole 15 one by one, and the stationary ring 4 and the stationary ring seat 5 are circumferentially positioned.
[0033] Furthermore, the inner end face of the stationary ring 4 is axially connected to the stepped surface of the second stepped hole 7 of the stationary ring seat 5 using a flexible connection structure. Specifically, the axial connection between the inner end face of the stationary ring 4 and the stepped surface of the second stepped hole 7 of the stationary ring seat 5 using a flexible connection structure means that a PTFE annular washer 19 is provided inside the second stepped hole 7 of the stationary ring seat 5. The PTFE annular washer 19 abuts against the stepped surface of the second stepped hole 7 and the inner end face of the stationary ring 4, thus creating a flexible connection between the inner end face of the stationary ring 4 and the stationary ring seat 5. The PTFE annular washer 19 has a notch for the first pin 6 to pass through.
[0034] like Figure 4 and Figure 5 As shown, the moving ring assembly also includes a moving ring seat 10. One end of the moving ring seat 10 is provided with a third step hole 11. The moving ring 8 is disposed in the third step hole 11 and connected by a second pin 20 to achieve circumferential positioning and synchronous rotation.
[0035] The elastic component is at least one set of wave springs 12, which are located at the tail of the moving ring seat 10. The tail of the moving ring seat 10 is provided with a retaining ring 13. The tail of the driving ring 3 is fixed on the rotating shaft 2. The front end of the driving ring 3 extends to the outer wall of the moving ring seat 10 and both are provided with a second circumferential positioning structure for synchronous rotation. One end of the wave spring 12 abuts against the retaining ring 13, and the other end abuts against the stepped surface 14 of the center hole of the driving ring 3, thereby pushing the moving ring 8 and the stationary ring 4 to fit tightly together.
[0036] like Figure 5 As shown, the inner wall of the central hole of the moving ring seat 10 is provided with a second annular groove 16, and a second sealing ring 17 is provided in the second annular groove 16. The inner wall of the second sealing ring 17 is tightly sealed to the moving ring 8. An annular gasket is also provided in the stepped surface of the moving ring seat 10 to support the bottom surface of the moving ring 8.
Claims
1. A mechanical seal for a screw pump, comprising a rotating shaft (2) passing through a pump cover (1), a stationary ring assembly, a rotating ring assembly, an elastic assembly, and a drive ring (3); an annular cavity is provided between the outer wall of the rotating shaft (2) and the inner wall of the pump cover (1), the stationary ring assembly, the rotating ring assembly, the elastic assembly, and the drive ring (3) are all sleeved outside the rotating shaft (2) and located in the annular cavity; the stationary ring assembly includes a stationary ring (4) and a stationary ring seat (5), the stationary ring seat (5) being located in a first stepped hole of the pump cover (1); characterized in that: The stationary ring (4) is floatingly connected in the second stepped hole (7) of the stationary ring seat (5) and connected by the first pin (6) set in the axial direction. There is a gap between the outer wall of the stationary ring (4) and the inner wall of the stepped hole of the stationary ring seat (5). There is a gap between the inner wall of the stationary ring (4) and the outer wall of the rotating shaft (2). The sealing end face of the stationary ring (4) extends out of the stationary ring seat (5) and is in close contact with the moving ring (8) of the moving ring assembly. The inner wall of the second stepped hole (7) of the stationary ring seat (5) is provided with a first annular groove (9). The first sealing ring (18) is provided in the first annular groove (9). The first sealing ring (18) abuts against the bottom surface of the first annular groove (9) and the outer wall of the stationary ring (4) respectively, so that the stationary ring (4) and the stationary ring seat (5) are softly connected in the radial direction. In addition, the inner end face of the stationary ring (4) and the stepped surface of the second stepped hole (7) of the stationary ring seat (5) are connected in the axial direction by a soft connection structure.
2. The mechanical seal for a screw pump according to claim 1, characterized in that: The moving ring assembly also includes a moving ring seat (10), one end of which is provided with a third step hole (11). The moving ring (8) is disposed in the third step hole (11) and connected by a second pin (20) to achieve circumferential positioning and synchronous rotation.
3. The mechanical seal for a screw pump according to claim 2, characterized in that: The elastic component is at least one set of wave springs (12), the wave springs (12) are located at the tail of the moving ring seat (10), the tail of the moving ring seat (10) is provided with a retaining ring (13); the tail of the driving ring (3) is fixed on the rotating shaft (2), the front end of the driving ring (3) extends to the outer wall of the moving ring seat (10) and both are provided with a second circumferential positioning structure for synchronous rotation of both, one end of the wave spring (12) abuts against the retaining ring (13), and the other end abuts against the stepped surface (14) of the center hole of the driving ring (3), thereby pushing the moving ring (8) and the stationary ring (4) to fit tightly.
4. The mechanical seal for a screw pump according to claim 2, characterized in that: The inner end of the stationary ring (4) is provided with multiple positioning holes (15), and the end face of the stepped hole of the stationary ring seat (5) is provided with first pins (6) whose positions and numbers are consistent with the positioning holes (15). The first pins (6) are embedded into the corresponding positioning holes (15) one by one, and the stationary ring (4) and the stationary ring seat (5) are circumferentially positioned.
5. The mechanical seal for a screw pump according to claim 2, characterized in that: The inner wall of the central hole of the moving ring seat (10) is provided with a second annular groove (16), and a second sealing ring (17) is provided in the second annular groove (16). The inner wall of the second sealing ring (17) is tightly sealed to the moving ring (8).
6. The mechanical seal for a screw pump according to claim 1, characterized in that: The axial soft connection structure between the inner end face of the stationary ring (4) and the step surface of the second step hole (7) of the stationary ring seat (5) means that a PTFE annular washer (19) is provided in the second step hole (7) of the stationary ring seat (5). The PTFE annular washer (19) abuts between the step surface of the second step hole (7) and the inner end face of the stationary ring (4), thereby making the inner end face of the stationary ring (4) and the stationary ring seat (5) softly connected. The PTFE annular washer (19) has a notch for the first pin (6) to pass through.