Two-stage partial flow refrigerant pump

Abstract

The application discloses a two-stage partial flow refrigerant pump and belongs to the refrigerant pump field. The two-stage partial flow refrigerant pump comprises a motor unit and a pump unit, the pump unit comprises a first-stage impeller volute and a second-stage impeller volute which are separated by an inter-stage baffle, wherein a first-stage impeller and a second-stage impeller are arranged on a rotating shaft which is driven by the motor unit, and a transition flow channel is further arranged to enable the refrigerant in the first-stage impeller volute to flow into the second-stage impeller volute after being pressurized. The two-stage impeller structure is adopted in the application, compared with the traditional single-stage impeller structure, the two-stage impeller structure can meet the demand of small flow and high lift, and the required rotating speed is smaller, the anti-cavitation performance of the refrigerant pump can be improved, and the service life of the refrigerant pump is prolonged. Moreover, the refrigerant pump adopts a shield motor structure, a shield sleeve is arranged between the motor stator and the rotating shaft to separate the motor stator and the rotating shaft, a part of the refrigerant in the second-stage turbine liquid shell can leak into the rotating shaft to realize cooling and lubrication, the leakage problem of the shaft seal of the traditional refrigerant pump is solved, and the refrigerant pump is safe and reliable.

Description

Technical Field

[0001] This invention belongs to the field of refrigerant pump technology and relates to a two-stage partial flow refrigerant pump. Background Technology

[0002] With the advent of the cloud computing era, data centers require high power and large-scale deployment, placing even greater demands on timely heat dissipation. Active liquid cooling technology, due to its advantages such as strong heat dissipation capacity, high integration, and good temperature uniformity, has become one of the important means of thermal management for future electronic devices. In an active liquid cooling system, the core component is the pump that drives the circulation of the liquid working fluid. The pump's flow rate and head directly affect the system's heat dissipation capacity, and its reliability is crucial for the system's stable and safe operation.

[0003] Traditional single-stage vane refrigerant pumps are prone to cavitation under low flow and high head conditions due to their high rotational speed, which shortens their lifespan. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of cavitation and short lifespan of refrigerant pumps in the prior art under low flow and high head conditions, and to provide a two-stage partial flow refrigerant pump.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, the present invention provides a two-stage partial flow refrigerant pump, characterized in that it includes a motor unit and a pump unit; the motor unit includes a motor housing; a motor stator is disposed inside the motor housing; a rotating shaft is supported on the motor housing by bearings; a motor rotor is connected to the rotating shaft; the pump unit includes a pump housing; the pump housing is connected to the motor housing; one end of the rotating shaft extends into the pump housing; a first-stage impeller and a second-stage impeller are sequentially disposed on the portion of the rotating shaft extending into the pump housing along the refrigerant flow direction; a first-stage impeller volute is disposed outside the first-stage impeller; a second-stage impeller volute is disposed outside the second-stage impeller; an interstage baffle is disposed between the first-stage impeller volute and the second-stage impeller volute;

[0007] The pump casing is provided with a refrigerant inlet and a refrigerant outlet; the pump casing is provided with a transition channel for the refrigerant in the first-stage impeller volute to flow into the second-stage impeller volute and for the refrigerant in the second-stage impeller volute to flow out of the pump casing; the first-stage impeller volute, the interstage baffle, and the second-stage impeller volute are located within the transition channel; the refrigerant inlet is connected to the first-stage impeller volute; the refrigerant outlet is connected to the transition channel.

[0008] A further improvement of the present invention is that:

[0009] The primary and secondary impellers are partial flow pump impellers, connected back-to-back on the rotating shaft.

[0010] The transition channel is a cylindrical structure; a channel is provided on the cylindrical structure; one end of the channel is provided with a transition channel inlet, and the other end is provided with a transition channel outlet.

[0011] A first groove is provided at one end of the transition channel where it mates with the first-stage impeller volute; a second groove is provided at the other end of the transition channel where it mates with the pump housing; the first and second grooves are used to house sealing devices; the transition channel is fixedly connected to the interstage baffle.

[0012] The interstage baffle and the mating surfaces of the first-stage impeller and the second-stage impeller are provided with several grooves to form a labyrinth seal between the first-stage impeller volute and the second-stage impeller volute.

[0013] The motor housing is a closed structure with an opening at the point where the shaft extends.

[0014] A shielding sleeve is provided between the motor stator and the rotating shaft; the shielding sleeve is in contact with the motor stator.

[0015] A bushing is provided on the rotating shaft; the bushing is located between the motor housing and the secondary impeller; the bushing is clearance-fitted with both the rotating shaft and the motor housing.

[0016] The rotating shaft and the motor rotor are designed as a single unit; the rotating shaft is a hollow shaft.

[0017] The rotating shaft has a shaft end nut located inside the pump housing at one end; the shaft end nut has several drainage holes.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention includes a motor unit and a pump unit. The motor unit provides power to the rotating shaft, which drives a first-stage impeller and a second-stage impeller connected to it to perform staged pressurization of the flowing refrigerant. An interstage baffle is provided between the two impeller casings to separate them, and a transition flow channel is provided to allow the refrigerant in the first-stage impeller casing to flow into the second-stage impeller casing after first-stage pressurization. This invention adopts a two-stage impeller structure. Compared with the traditional single-stage impeller structure, the two-stage impeller structure requires a lower rotational speed to meet the requirements of small flow rate and high head, which can improve the cavitation resistance of the refrigerant pump and extend its service life.

[0020] Furthermore, the first-stage and second-stage impellers are partial flow pump impellers. Partial flow pump blades are linearly radial, resulting in a simple structure. The refrigerant enters the impeller axially from the inlet, but not all of it is discharged; only a small amount of liquid is output, while the remainder continues to rotate at high speed within the annular channel. The relative speed between the refrigerant and the impeller is very low, resulting in minimal hydraulic loss. Moreover, the first-stage and second-stage impellers are connected back-to-back to the shaft, which helps balance some of the axial force, making the refrigerant pump performance more stable.

[0021] Furthermore, a channel is cleverly designed into the transition flow channel. The channel inlet connects to the outlet of the first-stage impeller volute, and the channel outlet connects to the inlet of the second-stage impeller volute. This allows the refrigerant to be rapidly pressurized in the first stage within the impeller volute and then flow into the second-stage impeller volute for further pressurization. After both stages of pressurization, the refrigerant can then flow out through the transition flow channel from the refrigerant outlet on the pump casing. This enables the refrigerant pump to quickly achieve two stages of refrigerant pressurization, improving the pump's operating efficiency.

[0022] Furthermore, several grooves are provided on the mating surfaces of the interstage baffle and the two impeller volutes to form a labyrinth seal between the first-stage and second-stage impeller volutes. The labyrinth seal offers excellent sealing performance under high-speed conditions, requires no lubrication, is frictionless, easy to maintain, and has a long service life. Simultaneously, this labyrinth seal allows a portion of the refrigerant to leak from the second-stage impeller volute to the first-stage impeller volute, carrying away the heat generated by mechanical friction within the pump and preventing the refrigerant from vaporizing and producing gas, thus reducing the pump's performance.

[0023] Furthermore, the refrigerant pump adopts a shielded motor structure. A shielding sleeve is installed between the motor stator and the motor shaft, and the shielding sleeve fits snugly against the motor stator. An opening is provided at the protruding part of the shaft in the electronic housing, while the rest is closed. The fit between the shaft sleeve and the shaft, and between the shaft sleeve and the motor housing, is a clearance fit. This allows a portion of the refrigerant in the secondary impeller volute to flow into the motor housing through the clearance. The shielding sleeve, located inside the motor housing, separates the motor stator from the shaft, solving the leakage problem at the shaft seal of traditional refrigerant pumps, ensuring safety and reliability. Simultaneously, the complete fit between the shielding sleeve and the motor stator allows the heat generated by the motor stator to be transferred to the refrigerant circulating inside the shielded motor, achieving better cooling. Making the motor a shielded structure enables the refrigerant pump to be oil-free and leak-free.

[0024] Furthermore, the shaft is hollow, and several drainage holes can be formed in the shaft end nut. Cooling of the motor is achieved by leaking a portion of the refrigerant through the shaft sleeve, passing through the bearing into the space formed by the shaft and the shielding sleeve, then flowing through the bearing into the internal space of the shaft, and finally exiting through the drainage holes in the shaft end nut to the inlet of the first-stage impeller volute. This achieves cooling of the motor and bearings, as well as lubrication of the bearings. Compared to oil lubrication, this prevents the refrigerant and lubricating oil from miscibly dissolving, which could lead to lubrication failure. The leakage rate can be adjusted by the gap between the shaft sleeve and the motor housing, as well as the size of the central bore of the hollow shaft, to ensure that the refrigerant can carry away sufficient heat and that the motor operates within its normal temperature range. The shaft end nut provides axial positioning of the shaft while also allowing the refrigerant to flow out. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a structural diagram of a two-stage partial flow refrigerant pump;

[0027] Figure 2 Diagram of the casing structure of a two-stage partial flow refrigerant pump;

[0028] Figure 3 This is a diagram of the transition channel structure;

[0029] Figure 4 This is a structural diagram of the impeller of a two-stage partial flow refrigerant pump.

[0030] Wherein: 1-Motor housing; 2-Motor stator; 3-Shielding sleeve; 4-First bearing; 5-Second bearing; 6-Rotating shaft; 7-Pump housing; 8-Shaft sleeve; 9-Second stage impeller volute; 10-Second stage impeller; 11-Interstage baffle; 12-First stage impeller; 13-First stage impeller volute; 14-Shaft end nut; 15-Transition flow channel; 16-First sealing ring; 17-Third sealing ring; 18-Second sealing ring; 19-Fourth sealing ring; 20-Bolt; 71-Refrigerant inlet; 72-Refrigerant outlet; 151-Transition flow channel stepped structure; 152-First groove; 153-First through hole; 154-Channel; 1541-Transition flow channel inlet; 1542-Transition flow channel outlet; 155-Second groove; 156-Second through hole. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0036] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] See Figure 1 This invention discloses a two-stage partial-flow refrigerant pump, comprising a motor unit and a pump unit. The motor unit includes a motor housing 1; a motor stator 2 is disposed inside the motor housing 1; a hollow shaft 6 is supported on the motor housing 1 by bearings; the shaft 6 and the motor rotor are designed as a single unit, and a shaft end nut 14 is provided at one end of the shaft 6 located inside the pump housing 7 for axial positioning of the shaft; the shaft end nut 14 is provided with several drainage holes for discharging refrigerant entering the shaft. The motor housing 1 is a closed structure with an opening at the protruding position of the shaft 6; a shielding sleeve 3 is disposed between the motor stator 2 and the shaft 6, fitting snugly against the motor stator 2; a bushing 8 is disposed on the shaft 6, located between the motor housing 1 and the secondary impeller 10, and the bushing 8 has a clearance fit with both the shaft 6 and the motor housing 1.

[0039] See Figure 2 The pump unit includes a pump housing 7, on which a refrigerant inlet 71 and a refrigerant outlet 72 are provided; the pump housing 7 is connected to the motor housing 1 by bolts 20; a transition flow channel 15 is provided inside the pump housing 7; one end of a rotating shaft 6 extends into the pump housing 7, and on the portion of the rotating shaft 6 extending into the pump housing 7, a first-stage impeller 12 and a second-stage impeller 10 are arranged back-to-back along the refrigerant flow direction; as shown... Figure 4 As shown, the primary impeller 12 and the secondary impeller 10 are partial flow pump impellers; a primary impeller volute 13 is provided outside the primary impeller 12, and a secondary impeller volute 9 is provided outside the secondary impeller 10; an interstage baffle 11 is provided between the primary impeller volute 13 and the secondary impeller volute 9, and several grooves are provided on the mating surfaces of the interstage baffle 11, the primary impeller 12, and the secondary impeller 10 to form a labyrinth seal between the primary impeller volute 13 and the secondary impeller volute 9. The primary impeller volute 13, the interstage baffle 11, and the secondary impeller volute 9 are located within the transition flow channel 15; a third sealing ring 17 is provided at the mating surface between the inner ring of the transition flow channel 15 and the motor housing 1, and a fourth sealing ring 19 is provided on the mating surface between the motor housing 1 and the pump housing 7.

[0040] See Figure 3The transition channel 15 is a cylindrical structure with a stepped transition channel structure 151 to achieve axial positioning between the transition channel 15 and the pump housing 7 and the first-stage impeller volute 13. A channel 154 is provided on the cylindrical structure, with a channel inlet 1541 at one end and a channel outlet 1542 at the other end. A first groove 152 is provided at the mating point between the transition channel 15 and the first-stage impeller volute 13 to accommodate a first sealing ring 16. A second groove 155 is provided at the mating point between the transition channel 15 and the pump housing 7 to accommodate a second sealing ring 18. Several through holes 153 are provided at the mating point between the transition channel 15 and the interstage baffle 11 to install screws for circumferential positioning of the interstage baffle 11. A through hole 156 is made on the transition channel 15 at the position corresponding to the outlet of the secondary impeller volute 9, so as to connect the outlet of the secondary impeller volute 9 with the refrigerant outlet 72 of the pump housing 7.

[0041] The working process of this invention is as follows:

[0042] The refrigerant inlet is connected to the first-stage impeller volute 13, the first-stage impeller volute outlet is connected to the inlet of the transition channel 15, the outlet of the transition channel 15 is connected to the inlet of the second-stage impeller volute 10, and the outlet of the second-stage impeller volute 10 is connected to the refrigerant outlet. The refrigerant enters the first-stage impeller volute 13 through the refrigerant inlet 71 of the pump casing 7. After being pressurized within the first-stage impeller volute 13, it is discharged from the first-stage impeller volute outlet to the transition channel inlet 1541, then through the transition channel 154 and out through the transition channel outlet 1542 to the space formed by the second-stage impeller volute 9 and the motor 1. The refrigerant is diverted by the fins on the second-stage impeller volute, then reaches the second-stage impeller inlet through the second-stage impeller volute inlet. After being pressurized by the second-stage impeller 10, it is discharged from the second-stage impeller volute outlet to the transition channel 156 and then out through the pump casing outlet 72.

[0043] Cooling of the motor is achieved by leaking a portion of the refrigerant through the bushing 8. This refrigerant then flows through the angular contact ball bearing 5 into the space formed by the shaft 6 and the shielding sleeve 3, then through the deep groove ball bearing 4 into the interior of the shaft 6, and finally out through the drain hole of the shaft end nut 14 to the inlet of the first-stage impeller. This process cools the motor and bearings, and lubricates the bearings. The amount of leakage can be adjusted by the gap between the bushing and the motor housing, as well as the diameter of the hollow shaft's central bore, to ensure that the refrigerant can remove sufficient heat and that the motor operates within its normal temperature range.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-stage partial flow cryogen pump characterized by, The application relates to a refrigerant pump, which comprises a motor unit and a pump unit; the motor unit comprises a motor shell (1); a motor stator (2) is arranged in the motor shell (1); a rotating shaft (6) is supported on the motor shell (1) through bearings; a motor rotor is connected to the rotating shaft (6); the pump unit comprises a pump shell (7); the pump shell (7) is connected with the motor shell (1) in a matched mode; one end of the rotating shaft (6) extends into the pump shell (7); a first-stage impeller (12) and a second-stage impeller (10) are arranged on the part of the rotating shaft (6) extending into the pump shell (7) in sequence along the refrigerant flow direction; a first-stage impeller volute (13) is arranged outside the first-stage impeller (12); a second-stage impeller volute (9) is arranged outside the second-stage impeller (10); an inter-stage baffle (11) is arranged between the first-stage impeller volute (13) and the second-stage impeller volute (9). The first-stage impeller (12) and the second-stage impeller (10) are partial flow pump impellers and are connected to the rotating shaft (6) in a back-to-back mode; a plurality of grooves are arranged on the matching surfaces of the first-stage impeller (12) and the second-stage impeller (10) and the inter-stage baffle (11) so as to form a labyrinth seal between the first-stage impeller volute (13) and the second-stage impeller volute (9); the rotating shaft (6) and the motor rotor are designed in an integrated mode; the rotating shaft (6) is a hollow shaft; an end nut (14) is arranged at one end of the rotating shaft (6) located in the pump shell (7); a plurality of leakage groove holes are arranged on the end nut (14). A refrigerant inlet (71) and a refrigerant outlet (72) are arranged on the pump shell (7); a transition flow channel (15) is arranged in the pump shell (7) and used for guiding the refrigerant in the first-stage impeller volute to flow into the second-stage impeller volute and guiding the refrigerant in the second-stage impeller volute to flow out of the pump shell (7); the first-stage impeller volute (13), the inter-stage baffle (11) and the second-stage impeller volute (9) are located in the transition flow channel (15); the refrigerant inlet (71) is communicated with the first-stage impeller volute (13); the refrigerant outlet (72) is communicated with the transition flow channel (15). The transition flow channel (15) is in a cylindrical structure; a channel (154) is formed in the cylindrical structure; a transition flow channel inlet (1541) is arranged at one end of the channel (154) and a transition flow channel outlet (1542) is arranged at the other end of the channel (154); a first groove (152) is arranged at the position where the transition flow channel (15) is matched with the first-stage impeller volute (13); a second groove (155) is arranged at the position where the transition flow channel (15) is matched with the pump shell (7); the first groove (152) and the second groove (155) are used for placing sealing devices; the transition flow channel (15) is fixedly connected with the inter-stage baffle (11).

2. The two-stage partial flow cryogen pump of claim 1, wherein, The motor shell (1) is in a closed structure and is provided with an opening at the position where the rotating shaft (6) extends out.

3. The two-stage partial flow cryopump of claim 2, wherein, A shielding sleeve (3) is arranged between the motor stator (2) and the rotating shaft (6); the shielding sleeve (3) is attached to the motor stator (2).

4. The two-stage partial flow cryogen pump of claim 3, wherein, The rotating shaft (6) is provided with a shaft sleeve (8); the shaft sleeve (8) is located between the motor shell (1) and the secondary impeller (10); the shaft sleeve (8) is gap-fitted with the rotating shaft (6) and the motor shell (1).

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