Low-temperature liquid hydrogen centrifugal pump without pump pool

Abstract

The invention discloses a pump-pool-free low-temperature liquid hydrogen centrifugal pump, and relates to the technical field of liquid hydrogen pumps, the pump-pool-free low-temperature liquid hydrogen centrifugal pump comprises a pump shell, the pump shell internally comprises a working cavity and a motor cavity, a pump body is arranged in the working cavity, a driving motor is arranged in the motor cavity, and the pump shell is provided with a suction inlet and a liquid outlet; a plurality of flow guide fixing frames are arranged between the inner side wall of the motor cavity and a stator of the driving motor, and flow passing channels connecting the working cavity and the liquid outlet are formed among the flow guide fixing frames, the pump shell and the motor stator. And the overflowing flow channel helps liquid pressurized by the working cavity to directly lubricate and cool the driving motor and the bearing, and the liquid is smoothly discharged from the liquid outlet. A pump pool structure and a motor cavity wall face through hole of a traditional low-temperature liquid hydrogen immersed centrifugal pump are omitted, the structure of the liquid hydrogen pumping device is simplified, the weight is reduced, and space is saved; and the liquid hydrogen fully cools and lubricates the motor and the bearing, and takes away heat and hydrogen through the liquid outlet in time, so that the running stability of the pump is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cryogenic submersible pumps, and in particular to a cryogenic liquid hydrogen centrifugal pump without a pump pool. Background Art

[0002] Hydrogen is not only a clean, efficient and sustainable secondary energy carrier, but also an important industrial raw material. With the official promulgation and implementation of national standards such as GB / T40045-2021 "Liquid Hydrogen for Hydrogen-Energy Vehicles" and GB / T40060-2021 "Technical Requirements for Storage and Transportation of Liquid Hydrogen" in November 2021, liquid hydrogen storage and transportation equipment has become particularly important. Liquid hydrogen pumps are key core equipment that improves energy efficiency, reduces costs, and is suitable for the marketization and large-scale application of the liquid hydrogen industry.

[0003] At present, most of the liquid hydrogen pumps on the market are submersible pumps. Liquid hydrogen submersible pumps need to use a liquid hydrogen pump pool as their installation platform. The motor and bearings of the liquid hydrogen submersible pump need to exchange heat and lubricate with the liquid hydrogen in the pump pool through the through holes on the pump casing. The liquid hydrogen entering the pump suction port flows along the bypass pipe to the liquid hydrogen pump discharge port after the impeller works. When the motor of the submersible pump generates a lot of heat, the small flow of liquid hydrogen in the pump pool through the through holes of the pump casing cannot take away the heat in time, causing the temperature of the motor to rise; and the boiling point of liquid hydrogen at normal pressure is low. The increase in the motor temperature will cause a large amount of liquid hydrogen to gasify. Hydrogen accumulates above the pump pool and may be sucked into the suction port of the submersible pump, affecting the stable operation of the pump; and the liquid hydrogen after the impeller works flows to the discharge port of the submersible pump through the bypass pipe with a more complex structure, which will cause a large flow loss, and the existence of the pump pool also increases the volume and structural complexity of the liquid hydrogen pumping device.

[0004] Therefore, how to design a low-temperature liquid hydrogen centrifugal pump without a pump pool so that it can fully cool and lubricate the motor and bearings while reducing the liquid hydrogen gasification caused by the heating of the pump and motor, and ensuring that the liquid hydrogen submersible pump can operate efficiently and stably for a long time while simplifying the structure is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the problems in the prior art that the liquid hydrogen submersible pump has a complex structure, needs to be installed on a submersible pump platform to operate, has unstable operation, and has large flow losses, the present invention provides a low-temperature liquid hydrogen centrifugal pump without a pump pool, which solves the problems that the motor and bearing of the liquid hydrogen submersible pump with a pump pool cannot be cooled in time, and the liquid hydrogen has large flow losses after leaving the impeller. The submersible pump has a reduced volume, a simplified structure, and is easy to install and maintain.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a low-temperature liquid hydrogen centrifugal pump without a pump pool, comprising a pump housing, the pump housing comprising an inlet pump cover, an intermediate pump cover, and an outlet pump cover connected in sequence, a suction port and a liquid discharge port are arranged in the pump housing, a working cavity and a motor cavity are arranged between the suction port and the liquid discharge port, the working cavity is located on the suction port side, the motor cavity is located near the liquid discharge port side, a pump body is arranged in the working cavity, the pump body comprises a pump shaft and a functional component for conveying liquid hydrogen installed on the pump shaft, and a driving motor is arranged in the motor cavity; the driving motor drives the functional component to work through the pump shaft;

[0007] A plurality of flow guide fixing frames are arranged between the outer wall surface of the motor stator of the drive motor and the inner wall surface of the motor cavity, and a flow passage connecting the working cavity and the liquid discharge port is formed between the flow guide fixing frames and the outer wall surface of the motor stator and the inner wall surface of the motor cavity.

[0008] Preferably, the functional components installed on the pump shaft include an inducer, a primary impeller, a primary guide vane, a secondary impeller and a secondary guide vane arranged in sequence along the liquid hydrogen transport direction.

[0009] Preferably, a spacer pump cover is arranged between the working cavity and the motor cavity, and the spacer pump cover is provided with spacer pump cover through holes with the same number as the guide fixing frame, and the spacer pump cover through holes connect the working cavity and the motor cavity; the pump shaft is installed and fixed by a lower bearing and an upper bearing, the lower bearing is installed at the spacer pump cover, and the upper bearing is installed near the outlet pump cover.

[0010] Preferably, the outlet pump cover is provided with outlet pump cover through holes having the same number as the flow guide fixing frame, and the outlet pump cover through holes connect the motor cavity and the drain port.

[0011] Preferably, the outlet pump cover is provided with two outlet flow holes, the outlet flow holes connect the motor cavity and the drain port, and a small amount of liquid hydrogen in the motor cavity can flow through the upper bearing and flow to the drain port through the outlet flow holes to lubricate and cool the upper bearing.

[0012] Preferably, the inner wall surface of the motor cavity is provided with sliding mounting grooves having the same number as the guide fixing frame, the outer wall surface of the guide fixing frame matches the sliding mounting grooves, and the guide fixing frame can be installed on the intermediate pump cover through the sliding mounting grooves.

[0013] Preferably, the outer side of the spacer pump cover is provided with spacer pump cover protrusions having the same number as the sliding installation grooves, and the spacer pump cover can be installed in the middle pump cover through the sliding installation grooves.

[0014] Preferably, the drain port and the motor cavity are connected and transitioned via a conical cylinder.

[0015] Preferably, the inlet pump cover and the outlet pump cover are penetrated and fixed by fixing studs, and the inlet pump cover, the intermediate pump cover and the outlet pump cover are assembled and fastened by the fixing studs; the suction port end of the pump housing is provided with an inlet flange, and the discharge port end of the pump housing is provided with an outlet flange.

[0016] The present invention also provides a working method based on the cryogenic liquid hydrogen centrifugal pump, which comprises the following steps:

[0017] After the centrifugal pump is started, liquid hydrogen enters the centrifugal pump through the suction port, enters the working chamber, and passes through the functional components arranged along the pump shaft in sequence. Under the guidance of the functional components, the liquid hydrogen flows into the motor chamber through the interval pump cover. Part of the liquid hydrogen flows through the flow channel composed of the inner wall of the motor chamber, the outer wall of the motor stator and the guide fixing frame, and cools the motor stator at the same time; part of the liquid hydrogen flows through the air gap between the motor stator and the motor rotor to cool the drive motor;

[0018] The two parts of liquid hydrogen merge at the side of the motor cavity near the outlet pump cover; most of the liquid hydrogen flows to the drain port through the outlet pump cover through hole set on the outlet pump cover, and then flows to the liquid hydrogen discharge pipe connected to the outlet flange; a small part of the liquid hydrogen flows through the upper bearing and then flows through the two outlet flow holes set on the outlet pump cover to the drain port, and then flows to the liquid hydrogen discharge pipe connected to the outlet flange to lubricate and cool the upper bearing.

[0019] In summary, compared with the prior art, the present invention provides a low-temperature liquid hydrogen centrifugal pump without a pump pool. The liquid hydrogen centrifugal pump eliminates the design of the traditional submersible pump that needs to use the pump pool as an installation platform, so that the liquid hydrogen flows directly into the motor cavity after passing through the impeller working cavity of the pump, effectively improving the heat dissipation capacity of the liquid hydrogen centrifugal pump motor and bearings, reducing the liquid hydrogen vaporized due to cooling the motor and bearings, and enhancing the lubrication effect of the bearings and motors, simplifying the structure of the liquid hydrogen centrifugal pump, and reducing the difficulty of installation. By arranging a guide fixing frame between the inner wall of the motor cavity and the outer wall of the drive motor stator, the flow loss of liquid hydrogen flowing from the working cavity through the motor cavity to the outlet is reduced, thereby improving the operating efficiency and use stability of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 It is a schematic diagram of the cross-sectional structure of the pump body of the present invention;

[0022] Figure 2 for Figure 1 Schematic diagram of the structure of the intermediate pump cover;

[0023] Figure 3 for Figure 1 A schematic diagram of the structure of the guide fixing frame;

[0024] Figure 4 for Figure 1 Schematic diagram of the interval pump cover structure;

[0025] Figure 5 for Figure 1 Schematic diagram of the outlet pump cover structure;

[0026] Figure 6 It is a schematic diagram of the pump housing of the present invention.

[0027] In the figure: pump housing-1; inlet pump cover-11; suction port-101; discharge port-102; inlet flange-103; outlet flange-104; sliding mounting groove-105; intermediate pump cover-12; interval pump cover-13; interval pump cover through hole-131; interval pump cover protrusion-132; outlet pump cover-14; outlet pump cover through hole-141; fixing stud-15; working chamber-2; inducer-21; first-stage impeller-22; first-stage guide vane-23; second-stage impeller-24; second-stage guide vane-25; pump shaft-27; motor chamber-3; guide frame-31; motor stator-32; motor rotor-33; upper bearing-34; outlet flow hole-35; lower bearing-36. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the three examples of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0029] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside", "between" and the like indicate positions or location relationships based on the attached Figure 1 The orientation or positional relationship shown is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0030] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0031] As attached Figure 1 As shown, it is a schematic diagram of the cross-sectional structure of the low-temperature liquid hydrogen centrifugal pump without a pump pool of the present invention, which includes a pump housing 1, and the pump housing 1 is composed of an inlet pump cover 11, an intermediate pump cover 12, and an outlet pump cover 14 connected in sequence. The pump housing 1 is provided with a suction port 101 and a discharge port 102, and a working chamber 2 and a motor chamber 3 are provided between the suction port 101 and the discharge port 102. The low-temperature liquid hydrogen centrifugal pump can be installed in a horizontal, vertical, inclined, or other manner. Taking vertical installation as an example, after the low-temperature liquid hydrogen centrifugal pump is vertically installed, the working chamber 2 is arranged above the suction port 101, the motor chamber 3 is arranged above the working chamber 2, and the discharge port 102 is arranged at the top of the pump housing 1. The discharge port 102 and the motor chamber 3 are connected and transitioned through a conical cylinder. The pump housing 1 is connected to the liquid hydrogen input pipeline through an inlet flange 103 arranged on the side of the suction port 101, and the pump housing 1 is connected to the liquid hydrogen discharge pipeline through an outlet flange 104 arranged on the side of the discharge port 102.

[0032] The working chamber 2 is provided with a pump body, which includes a pump shaft 26 and functional components mounted on the pump shaft 26. The motor chamber 3 is provided with a drive motor, and the output shaft of the drive motor can be coaxially connected to the pump shaft, or can be connected to the pump shaft as shown in FIG. Figure 1 The figure shows an integrated structure. When working, the driving motor drives the functional components to rotate, thereby realizing the transportation of liquid hydrogen from the low-pressure area to the high-pressure area.

[0033] The functional component is used to realize the pressurized delivery of liquid hydrogen. In an optional embodiment of the present invention, the functional component includes an inducer 21, a primary impeller 22, a primary guide vane 23, a secondary impeller 24 and a secondary guide vane 25 arranged in sequence. It should be noted that the specific composition structure, impeller stage number and guide vane stage number of the functional component are not limited to this solution.

[0034] Reference Figure 2 Schematic diagram of the intermediate pump cover structure and attached Figure 3Schematic diagram of the structure of the flow guide fixing frame, a plurality of flow guide fixing frames 31 are arranged between the outer wall surface of the motor stator 32 of the driving motor and the inner wall surface of the motor cavity 3. In a preferred embodiment of the present invention, the plurality of flow guide fixing frames 31 are arranged at equal intervals along the circumferential direction of the inner wall surface of the motor cavity 3, and each flow guide fixing frame 31 itself has a certain length, width and thickness, and its length direction is the axial direction of the pump housing, and its thickness direction is the radial direction of the pump housing. A flow passage connecting the working cavity 2 and the discharge port 102 is formed between the flow guide fixing frame 31 and the outer wall surface of the motor stator 32 and the inner wall surface of the motor cavity 3, wherein the width of the flow passage is determined by the circumferential distance between two adjacent flow guide fixing frames 31, and the length and thickness of the flow passage are respectively determined by the length and thickness of the flow guide fixing frame 31. To facilitate installation, the intermediate pump cover 12 is provided with the same number of sliding mounting grooves 105 as the guide frame 31 , the outer wall surface of the guide frame 31 matches the sliding mounting grooves 105 , and the guide frame 31 can be installed on the intermediate pump cover 12 through the sliding mounting grooves 105 .

[0035] Specifically, in this embodiment, the number of the guide fixing frames 31 is eight. The specific number of the guide fixing frames 31 is not a limitation of this solution.

[0036] In one embodiment of the present invention, the pump shaft 26 and the output shaft of the drive motor are an integrated structure. In order to fix the pump shaft 26 and ensure smooth operation, the pump shaft 26 is installed and fixed by a lower bearing 36 and an upper bearing 34, and passes through the motor rotor 33 of the drive motor.

[0037] Attached Figure 4 For attachment Figure 1 The schematic diagram of the structure of the intermediate pump cover 13 is shown in FIG. 1 . The intermediate pump cover 13 is arranged in the intermediate pump cover 12 to separate the working chamber 2 and the motor chamber 3. Figure 4 As shown, the spacer pump cover 13 is provided with the same number of spacer pump cover through holes 131 as the flow guide fixing frame 31, and the spacer pump cover through holes 131 connect the working chamber 2 and the motor chamber 3. The spacer pump cover 13 is provided with the same number of spacer pump cover protrusions 132 as the sliding installation grooves 105 on the outside, and the spacer pump cover 13 can be installed in the middle pump cover 12 through the cooperation between the spacer pump cover protrusions 132 and the sliding installation grooves 105.

[0038] Attached Figure 5 For attachment Figure 1 The structural diagram of the middle outlet pump cover 14. Figure 5 As shown, the outlet pump cover 14 is provided with outlet pump cover through holes 141 having the same number as the flow guide fixing frame 31 , and the outlet pump cover through holes 141 communicate with the motor cavity 3 and the liquid discharge port 102 .

[0039] In a specific embodiment of the present invention, Figure 1As shown, the suction port 101 is arranged at the bottom of the inlet pump cover 11, and the discharge port 102 is arranged at the top of the outlet pump cover 14. Figure 1 As shown, the upper bearing 34 is installed near the outlet pump cover 14, and the lower bearing 36 is installed at the interval pump cover 13.

[0040] In a specific embodiment of the present invention, Figure 1 As shown, the outlet pump cover 14 is provided with two outlet flow holes 35 , which connect the motor cavity 3 and the drain port 102 . A small amount of liquid hydrogen in the motor cavity 3 can flow through the upper bearing 34 and flow to the drain port 102 through the outlet flow holes 35 to lubricate and cool the upper bearing 34 .

[0041] When the centrifugal pump is started, liquid hydrogen enters the centrifugal pump through the suction port 101, enters the working chamber 2, passes through the functional components arranged along the pump shaft 26 in sequence, and flows into the motor chamber 3 through the interval pump cover through hole 131 arranged on the interval pump cover 13 under the guidance of the last stage of the guide vane. Part of the liquid hydrogen flows through the flow channel formed by the inner wall of the motor chamber 3, the outer wall of the motor stator 32 and the guide fixing frame 31, and cools the motor stator at the same time; part of the liquid hydrogen flows through the air gap between the motor stator 32 and the motor rotor 33, and cools the drive motor. The two parts of liquid hydrogen meet at the motor chamber 3 near the outlet pump cover 14 side. Most of the liquid hydrogen flows to the discharge port 102 through the outlet pump cover through hole 141 provided on the outlet pump cover 14, and then flows to the liquid hydrogen discharge pipeline connected to the outlet flange 104; a small part of the liquid hydrogen flows through the upper bearing 34 and then flows through the two outlet flow holes 35 provided on the outlet pump cover 14 to the discharge port 102, and then flows to the liquid hydrogen discharge pipeline connected to the outlet flange 104. The above scheme combines the liquid hydrogen transportation with the heat dissipation and lubrication of the drive motor and the rotating mechanism, cancels the traditional pump pool structure, reduces the overall volume of the device, and reduces the flow resistance of liquid hydrogen during the pump transportation process, improves the efficiency of cooling and lubrication of the drive motor and the rotating mechanism, and effectively ensures the high efficiency and stability of the pump pool-free liquid hydrogen centrifugal pump.

[0042] As an optional implementation, the number of interval pump cover through holes 131 set on the interval pump cover 13 can be different from the number of the diversion fixing frame 31, and the number of outlet pump cover through holes 141 set on the outlet pump cover 14 can be different from the number of the diversion fixing frame 31. The number of interval pump cover through holes 131 and the number of outlet pump cover through holes 141 are not limited to this solution.

[0043] The shape of the guide fixing frame 31 may also be other shapes, and the shape of the guide fixing frame 31 is not a limitation of this solution.

[0044] Attached Figure 6 Schematic diagram of the structure of the liquid hydrogen centrifugal pump housing 1. Figure 6As shown, the inlet pump cover 11 and the outlet pump cover 14 of the pump housing 1 are penetrated and fixed by eight fixing bolts 15 , and the inlet pump cover 11 , the middle pump cover 12 , and the outlet pump cover 14 are assembled and fastened by the fixing bolts 15 .

[0045] As an optional implementation, in order to prevent the loss of cold, a vacuum jacket and an insulation layer may be provided on the outside of the pump housing for thermal insulation.

[0046] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A low-temperature liquid hydrogen centrifugal pump without a pump pool, comprising a pump housing (1), characterized in that: The pump housing comprises an inlet pump cover (11), an intermediate pump cover (12), and an outlet pump cover (14) which are connected in sequence. A suction port (101) and a liquid discharge port (102) are provided in the pump housing (1). A working chamber (2) and a motor chamber (3) are provided between the suction port (101) and the liquid discharge port (102). The working chamber (2) is located on the suction port side, and the motor chamber (3) is located close to the liquid discharge port side. A pump body is provided in the working chamber (2). The pump body comprises a pump shaft (26) and a functional component for conveying liquid hydrogen installed on the pump shaft (26). A driving motor is provided in the motor chamber (3); the driving motor drives the functional component to work through the pump shaft (26); A plurality of flow guide fixing frames (31) are provided between the outer wall surface of the motor stator (32) of the drive motor and the inner wall surface of the motor cavity (3); a flow passage connecting the working cavity (2) and the liquid discharge port (102) is formed between the flow guide fixing frames (31) and the outer wall surface of the motor stator (32) and the inner wall surface of the motor cavity (3).

2. A low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 1, characterized in that: The functional components installed on the pump shaft (26) include an inducer (21), a first-stage impeller (22), a first-stage guide vane (23), a second-stage impeller (24) and a second-stage guide vane (25) which are arranged in sequence along the liquid hydrogen conveying direction.

3. A low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 1, characterized in that: A spacer pump cover (13) is arranged between the working chamber (2) and the motor chamber (3); the spacer pump cover (13) is provided with spacer pump cover through holes (131) the same number as the flow guide fixing frame (31); the spacer pump cover through holes (131) communicate with the working chamber (2) and the motor chamber (3); the pump shaft (26) is installed and fixed by means of a lower bearing (36) and an upper bearing (34); the lower bearing (36) is installed at the spacer pump cover (13), and the upper bearing (34) is installed near the outlet pump cover (14).

4. A low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 1, characterized in that: The outlet pump cover (14) is provided with outlet pump cover through holes (141) having the same number as the flow guide fixing frame (31), and the outlet pump cover through holes (141) are connected between the motor cavity (3) and the liquid discharge port (102).

5. A low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 3, characterized in that: The outlet pump cover (14) is provided with two outlet flow holes (35), and the outlet flow holes (35) are connected with the motor cavity (3) and the liquid discharge port (102). A small amount of liquid hydrogen in the motor cavity (3) can flow through the upper bearing (34) and flow to the liquid discharge port (102) through the outlet flow holes (35) to lubricate and cool the upper bearing (34).

6. A low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 3, characterized in that: The inner wall surface of the motor cavity (3) is provided with sliding installation grooves (105) having the same number as the guide fixing frame (31); the outer wall surface of the guide fixing frame (31) matches the sliding installation grooves (105); and the guide fixing frame (31) can be installed on the intermediate pump cover (12) through the sliding installation grooves (105).

7. A low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 6, characterized in that: The outer side of the spacer pump cover (13) is provided with spacer pump cover protrusions (132) having the same number as the sliding installation grooves (105), and the spacer pump cover (13) can be installed in the middle pump cover (12) through the sliding installation grooves (105).

8. The low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 1, characterized in that: The liquid discharge port (102) and the motor cavity (3) are connected and transitioned via a conical cylinder.

9. The low-temperature liquid hydrogen centrifugal pump without a pump pool according to claim 1, characterized in that: The inlet pump cover (11) and the outlet pump cover (14) are penetrated and fixed by fixing studs (15), and the inlet pump cover (11), the intermediate pump cover (12) and the outlet pump cover (14) are assembled and fastened by the fixing studs (15); the suction port (101) end of the pump housing (1) is provided with an inlet flange (103), and the discharge port (102) end of the pump housing (1) is provided with an outlet flange (104).

10. A working method based on the cryogenic liquid hydrogen centrifugal pump according to claim 5, characterized in that: The steps include: After the centrifugal pump is started, liquid hydrogen enters the centrifugal pump through the suction port, enters the working chamber, and passes through the functional components arranged along the pump shaft in sequence. Under the guidance of the functional components, the liquid hydrogen flows into the motor chamber through the interval pump cover. Part of the liquid hydrogen flows through the flow channel composed of the inner wall of the motor chamber, the outer wall of the motor stator and the guide fixing frame, and cools the motor stator at the same time; part of the liquid hydrogen flows through the air gap between the motor stator and the motor rotor to cool the drive motor; The two parts of liquid hydrogen merge at the side of the motor cavity near the outlet pump cover; most of the liquid hydrogen flows to the drain port through the outlet pump cover through hole set on the outlet pump cover, and then flows to the liquid hydrogen discharge pipe connected to the outlet flange; a small part of the liquid hydrogen flows through the upper bearing and then flows through the two outlet flow holes set on the outlet pump cover to the drain port, and then flows to the liquid hydrogen discharge pipe connected to the outlet flange to lubricate and cool the upper bearing.

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