Dry gas seal cryogenic liquid car filling pump

Abstract

The utility model relates to the technical field of filling pump, especially to a low temperature liquid filling pump with dry gas seal. The filling pump comprises a base, a motor, a pump shell and a centrifugal impeller. The motor shaft is rigidly connected with the pump shaft, and the pump shaft is provided with the centrifugal impeller. The pump shell is connected with an inlet and an outlet connector, and is internally provided with a static ring seat. An elastic element is arranged in the guide cavity of the static ring seat, and the elastic element is connected with the static ring. The output shaft is correspondingly provided with a movable ring. The sealing shell, the pump shell and the like jointly form a gas sealing cavity. The sealing shell is provided with an air inlet and an air outlet which are in communication with the gas sealing cavity. During sealing, the sealing gas enters through the inlet connector, and the movable ring rotates to drive the gas to enter the space between the movable ring and the static ring. The elastic element is contracted to separate the movable ring and the static ring to form a gas film, so that non-contact operation is realized, dry friction is reduced, and the service life is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of vehicle filling pump technology, and in particular to a dry gas-sealed cryogenic liquid vehicle filling pump. Background Technology

[0002] As a key conveying equipment for the sale of cryogenic liquid products (liquid oxygen, liquid nitrogen, and liquid argon) in the air separation backup unit, the vehicle filling pump needs to be frequently started and stopped to cooperate with vehicles for filling operations, resulting in a high daily operation frequency.

[0003] Currently, the pump bodies designed by the original manufacturer mainly use mechanical seals, but these seals have significant defects in actual operation: during each start-up and shutdown, due to the pump body's own cooling or insufficient liquid cooling during the initial start-up, an effective liquid film cannot form between the dynamic and static rings. This results in the two end faces being tightly pressed together and difficult to separate at the moment the motor starts, leading to dry wear. This problem directly shortens the service life of the mechanical seal, increases the frequency of spare parts replacement, and causes overall maintenance costs to rise.

[0004] Meanwhile, the selection of seals in this scenario faces multiple challenges: First, the lowest medium temperature can reach -196℃, while conventional silicone rubber seals can only withstand temperatures as low as -50℃, and even extreme rubber seals can only be used for static sealing at -100℃; Second, due to the extremely low operating temperature and limited installation space, it is impossible to flush the mechanical seal. When the medium (liquid nitrogen, liquid oxygen, liquid argon) leaks through the sealing end face, it will vaporize into a gaseous state at the end face, causing the sealing end face to be in a dry wear state, which seriously affects the long-term use of the seal; Third, the frequent start-up and shutdown of the cryogenic charging pump further aggravates the wear of the sealing end face. Utility Model Content

[0005] In view of this, the present invention provides a dry gas-sealed cryogenic liquid vehicle filling pump.

[0006] Therefore, the present invention provides the following technical solution:

[0007] A dry gas-sealed cryogenic liquid vehicle filling pump includes a base, a motor, a protective cover, a pump casing, and a centrifugal impeller. The motor is mounted on the base, and its output shaft passes through the protective cover, with its end located inside the pump casing and fitted with a centrifugal impeller. The sealing shell communicates with the pump casing. An inlet pipe is connected to the axial port of the pump casing, and an outlet pipe is connected to the radial port of the pump casing. A stationary ring seat is installed inside the pump casing, and a guide cavity is provided inside the stationary ring seat. An elastic element is installed inside the guide cavity, and the free end of the elastic element is connected to the stationary ring. A rotating ring is installed on the output shaft corresponding to the stationary ring. The sealing shell, pump casing, stationary ring seat, output shaft, stationary ring, and rotating ring together constitute a gas-sealed cavity. The protective cover has an air inlet and an air outlet, both of which communicate with the gas-sealed cavity.

[0008] The end face of the moving ring facing the stationary ring is provided with an involute groove.

[0009] The free end of the elastic element is connected to a push ring, and the push ring and the stationary ring are connected along the axial direction of the output shaft. The radial inner surfaces of the two rings together form an annular groove, and a push ring is installed in the annular groove.

[0010] A retaining ring is installed at the end of the stationary ring seat and on the outside of the stationary ring. A limiting groove is provided on the inner side of the retaining ring, and a limiting block is provided on the outer side of the stationary ring corresponding to the limiting groove.

[0011] A sealing ring is installed between the stationary ring seat and the pump casing.

[0012] The end of the output shaft is connected to the impeller shaft, the impeller and the moving ring are mounted on the impeller shaft, and an annular stacked gasket is installed on the impeller shaft between the moving ring and the output shaft.

[0013] The axial port of the pump casing is connected to a connecting pipe, and the end of the connecting pipe away from the pump casing is connected to a flexible connecting pipe. The other end of the flexible connecting pipe is connected to the inlet connecting pipe.

[0014] The elastic element is a bellows.

[0015] Advantages and positive effects of this utility model:

[0016] During sealing operation, sealing gas is introduced into the gas sealing chamber inside the pump casing through the inlet pipe. The sealing gas reaches the end face of the rotating ring, which rotates rapidly under the drive of the motor output shaft, driving the sealing gas into the space between the rotating ring and the stationary ring. The elastic element contracts under the action of gas pressure, and the rotating ring and the stationary ring separate from each other, forming a gas film between their contact surfaces. This achieves non-contact operation of the sealing end face, reduces dry friction between the contact surfaces, and increases service life. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A front view of a dry gas-sealed cryogenic liquid vehicle filling pump provided by this utility model.

[0019] Figure 2 A cross-sectional view of the sealing structure of a dry gas-sealed cryogenic liquid vehicle filling pump provided by this utility model.

[0020] Figure 3 A half-sectional view of the sealing structure of a dry gas-sealed cryogenic liquid filling pump provided by this utility model.

[0021] Figure 4 This utility model provides a structural diagram of the dynamic ring sealing end face of a sealing structure for a dry gas-sealed cryogenic liquid vehicle filling pump.

[0022] In the diagram: 1. Base; 2. Motor; 3. Protective cover; 4. Pump casing; 5. Centrifugal impeller; 6. Output shaft; 7. Outlet pipe; 8. Inlet pipe; 9. Stationary ring seat; 10. Guide cavity; 11. Elastic element; 12. Stationary ring; 13. Moving ring; 14. Air seal cavity; 15. Air inlet; 16. Air outlet; 17. Annular groove; 18. Push ring; 19. Retaining ring; 20. Limiting groove; 21. Limiting block; 22. Sealing ring; 23. Impeller shaft; 24. Stacked gasket; 25. Involute groove; 26. Connecting pipe; 27. Flexible pipe; 28. Push ring. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0024] This utility model provides a dry gas-sealed cryogenic liquid filling pump, such as... Figure 1-4 As shown, the pump includes a base 1, a motor 2, a protective cover 3, a pump casing 4, and a centrifugal impeller 5. The motor 2 is mounted on the base 1, and the output shaft 6 of the motor 2 passes through the protective cover 3. Its end is located inside the pump casing 4 and the centrifugal impeller 5 is mounted through the impeller shaft 23. The centrifugal impeller 5 rotates synchronously with the output shaft 6 to achieve liquid delivery.

[0025] like Figure 1 As shown, the pump casing 4 serves as the core cavity for fluid transport. Its axial port is connected to the inlet pipe 8 via connecting pipe 26 and flexible connecting pipe 27, while its radial port is directly connected to the outlet pipe 7, forming a complete liquid inlet and outlet channel. The protective cover 3 is connected to the pump casing 4, and the two, along with surrounding components, together constitute the installation foundation of the sealing system.

[0026] like Figure 2-3 As shown, a stationary ring seat 9 is installed inside the pump casing 4. A guide cavity 10 is provided inside the stationary ring seat 9. A bellows with an elastic element 11 is installed inside the guide cavity 10. The free end of the bellows is connected to a push ring 28. The push ring 28 and the stationary ring 12 are axially connected along the output shaft 6. Their radially inner surfaces enclose each other to form an annular groove 17, in which a push ring 18 is installed. A moving ring 13 is installed on the output shaft 6 at a position corresponding to the stationary ring 12. Figure 4As shown, the end face of the rotating ring 13 facing the stationary ring 12 is machined with an involute groove 25, which enhances the stability of the sealing gas film through a special fluid dynamic pressure groove design. The protective cover 3, pump housing 4, stationary ring seat 9, output shaft 6, stationary ring 12 and rotating ring 13 together enclose the gas sealing cavity 14. The air inlet 15 and air outlet 16 on the protective cover 3 are connected to the gas sealing cavity 14 to realize the circulation of sealing gas.

[0027] A retaining ring 19 is installed at the end of the stationary ring seat 9, located on the outer side of the stationary ring. A limiting groove 20 is provided on the inner side of the retaining ring 19. A limiting block 21 is provided on the outer side of the stationary ring 12 corresponding to the limiting groove 20 to limit the displacement of the stationary ring 12 along the expansion and contraction direction of the bellows. A sealing ring 22 is installed between the stationary ring seat 9 and the pump casing 4 to ensure the sealing performance of the cavity. An annular stacked gasket 24 is installed on the impeller shaft 23 between the moving ring 13 and the output shaft 6 to compensate for axial error and buffer vibration.

[0028] During sealing operation, pure nitrogen gas at 0.4 MPa and with a purity of 99.999% is introduced into the gas sealing cavity 14 through the air inlet 15. The gas then reaches the end face of the rotating ring 13 via the gas sealing cavity 14. As the rotating ring 13 rotates at high speed with the output shaft 6, the involute groove 25 guides the sealing gas from the outer radial center. The gas is compressed within the gap between the rotating and stationary rings, and the pressure increases to form a gas film. Under the action of gas pressure, the bellows contracts, causing the rotating ring 13 to separate from the stationary ring 12, achieving non-contact operation and significantly reducing friction loss.

[0029] The sealing gas is eventually discharged through the outlet 16, carrying away any trace amounts of liquid vapor that may leak, thus maintaining a stable environment inside the sealed cavity.

[0030] This application removes the rubber sealing ring between the stationary ring 12 and the bellows, and ensures the flatness of the contact surface (≤0.005mm) through precision grinding. Sealing is achieved through direct metal-to-metal contact, preventing rubber aging and failure at low temperatures. Continuous purging with 0.4MPa pure nitrogen heats the sealing area, vaporizing any potential leaks and replenishing the sealing gas supply. It also promptly removes leaked gas, maintaining gas film stability.

[0031] The dry gas sealing assembly of this application underwent bench testing, and the sealing leakage was consistently controlled at <0.9 g / L. After disassembly, the sealing end face remained intact and undamaged. The motor was started and stopped 20 times consecutively within 20 minutes, simulating frequent start-stop conditions in the field; the sealing end face showed no scratches, proving its impact resistance. The liquid nitrogen filling pump seal has been operating stably for 61 months, and the liquid oxygen filling pump seal has been operating stably for 37 months, with all performance indicators remaining normal.

[0032] Statistics show that the cost of a single original imported mechanical seal is 23,000 yuan, and a single pump needs to be replaced twice a year, resulting in a total cost of 4.6 million yuan for 5 pumps over 20 years. The cost of a single dry gas seal of this utility model is 25,000 yuan, with a one-time investment of 125,000 yuan for 5 pumps, and a theoretical lifespan of 20 years. Over 20 years, this translates to a cumulative cost saving of 4.475 million yuan, with an average annual saving of 223,750 yuan in spare parts costs, demonstrating significant economic benefits.

[0033] In summary, this embodiment, through its innovative dry gas sealing structure design and continuous nitrogen purging process, effectively solves the sealing wear problem caused by frequent start-stop and incomplete liquid cooling in cryogenic liquid charging pumps. It also boasts advantages such as long service life, low maintenance, and high economy, making it suitable for widespread application in the field of cryogenic liquid transportation.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A dry gas sealed cryogenic liquid transfer pump characterized by, The pump casing includes a base (1), a motor (2), a protective cover (3), a pump housing (4), and a centrifugal impeller (5). The motor (2) is mounted on the base (1), and the output shaft (6) of the motor (2) passes through the protective cover (3). Its end is located inside the pump housing (4) and a centrifugal impeller (5) is installed thereon. The protective cover (3) is connected to the pump housing (4). An inlet pipe (8) is connected to the axial port of the pump housing (4), and an outlet pipe (7) is connected to the radial port of the pump housing (4). A stationary ring seat (9) is installed inside the pump housing (4), and the stationary ring seat (9) is provided with A guide cavity (10) is provided, and an elastic element (11) is installed inside the guide cavity (10). The free end of the elastic element (11) is connected to a stationary ring (12). A rotating ring (13) is installed on the output shaft (6) corresponding to the stationary ring (12). The protective cover (3), pump housing (4), stationary ring seat (9), output shaft (6), stationary ring (12) and rotating ring (13) together constitute an air seal cavity (14). An air inlet (15) and an air outlet (16) are provided on the protective cover (3). Both the air inlet (15) and the air outlet (16) are connected to the air seal cavity (14).

2. A dry gas sealed, low temperature liquid filled pump as claimed in claim 1, wherein, The moving ring (13) has an involute groove (25) on its end face facing the stationary ring (12).

3. A dry gas sealed, low temperature liquid filled pump as defined in claim 1 wherein, The free end of the elastic element (11) is connected to the push ring (28). The push ring (28) and the stationary ring (12) are connected along the axial direction of the output shaft (6). The radial inner surfaces of the two together form an annular groove (17). A push ring (18) is installed in the annular groove (17).

4. A dry gas sealed, low temperature liquid filled pump as defined in claim 1, wherein, A retaining ring (19) is installed at the end of the stationary ring seat (9) and on the outside of the stationary ring. A limiting groove (20) is provided on the inner side of the retaining ring (19), and a limiting block (21) is provided on the outer side of the stationary ring (12) corresponding to the limiting groove (20).

5. A dry gas-sealed cryogenic liquid filling pump according to claim 1, characterized in that, A sealing ring (22) is installed between the stationary ring seat (9) and the pump casing (4).

6. A dry gas sealed, low temperature liquid filled pump as defined in claim 1, wherein, The end of the output shaft (6) is connected to the impeller shaft (23). The impeller (5) and the moving ring (13) are mounted on the impeller shaft (23). An annular stacked gasket (24) is installed on the impeller shaft (23) between the moving ring (13) and the output shaft (6).

7. A dry gas sealed, low temperature liquid filled pump as defined in claim 1 wherein, The axial port of the pump casing (4) is connected to a connecting pipe (26), and the end of the connecting pipe (26) away from the pump casing (4) is connected to a flexible connecting pipe (27). The other end of the flexible connecting pipe (27) is connected to the inlet connecting pipe (8).

8. A dry gas sealed, low temperature liquid filled pump as defined in claim 1, wherein, The elastic element (11) is a bellows.

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