A sealing structure for a hydrogen circulation pump of a fuel cell

Abstract

The present invention belongs to the field of fuel cell technology. A fuel cell hydrogen circulation pump sealing structure is formed between one side of a pump body (1) and a cover plate (2). A motor (4) is installed on the other side of the pump body (1). An impeller (15) is installed at one end of a motor rotor shaft (5) of the motor (4) extending into the air cavity (3). A thrust sleeve I (6) and a thrust sleeve II (7) are installed between the motor rotor shaft (5) and the pump body (1). The outer ring of the thrust sleeve I (6) is provided with multiple grooves (A). The outer ring of the thrust sleeve II (7) is provided with multiple grooves (A). A piston ring (8) is installed in each groove (A). The multiple piston rings (8) form a labyrinth seal structure. The fuel cell hydrogen circulation pump sealing structure of the present invention improves the sealing effect, prevents water from entering the interior of the bearing and the interior of the motor, prolongs the service life of the circulation pump, reduces the sealing cost, and reduces the maintenance cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and more particularly, relates to a sealing structure of a hydrogen circulation pump of a fuel cell. Background Art

[0002] Fuel cells generate electricity through an electrochemical reaction between hydrogen and oxygen in the air. This is a process that converts chemical energy into electrical energy, accompanied by the production of water. In practical applications, the supply of hydrogen is generally greater than the amount required for the electrochemical reaction. To save energy and prevent hydrogen from being directly discharged into the air, causing environmental pollution and the risk of explosion, this hydrogen needs to be recovered and reused using a hydrogen circulation pump. Because the recovered hydrogen contains a large amount of water vapor and some liquid water, if the seal between the air cavity and the motor is poor, water can enter the bearings and the motor, causing rust and damage to the bearings and the motor. To address this technical problem, the existing technology generally has two solutions. One is to use a disc motor with better sealing performance and ceramic bearings with better water resistance, but this is more expensive; the other is to use air seals or mechanical seals, but these products have a shorter lifespan. Therefore, there is room for further improvement in the existing technology.

[0003] The prior art includes a technology named "A Hydrogen Circulation Pump for Fuel Cells" and a publication number of "CN116576109A". This technology relates to the field of fuel cell technology, and in particular to a hydrogen circulation pump for fuel cells. The technology comprises a motor housing, a pump housing, and a bearing seat. A junction box is mounted on the motor housing, and a terminal sealing structure is provided in the junction box. A stator, a rotor, and a motor shaft are provided in the motor housing. The motor shaft is connected to the driving shaft in the gear chamber via a plug-in positioning structure. The plug-in positioning structure is used to radially position the motor shaft and the driving shaft. An air inlet and an air outlet are provided on the pump housing. The inner wall of the pump housing is provided with connecting grooves on both sides of the air outlet. One side of the connecting groove leads to the air outlet, and the other side leads to the bottom of the curved inner wall of the pump housing. The connecting groove can discharge water remaining at the bottom of the curved inner wall of the pump housing to the air outlet, preventing water from remaining in the pump housing and freezing the rotor, thereby improving the ice-breaking effect and reducing the noise generated by the impact of concentrated backflow of high-pressure gas. The terminal sealing structure improves the airtightness of the hydrogen circulation pump. However, this technology does not involve the technical problems and technical solutions of the present application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a fuel cell hydrogen circulation pump sealing structure with a simple structure is provided, which effectively improves the sealing effect by combining labyrinth sealing with pressure control, prevents water from entering the inside of the bearing and the inside of the motor, increases the service life of the circulation pump, reduces the sealing cost, and reduces the maintenance cost of the circulation pump.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is:

[0006] The present invention is a sealing structure for a fuel cell hydrogen circulation pump. An air cavity is formed between one side of the pump body of the circulation pump and the cover plate. A motor is installed on the other side of the pump body. An impeller is installed at one end of the motor rotor shaft extending into the air cavity. Thrust sleeve I and thrust sleeve II are installed between the motor rotor shaft and the pump body. The outer ring of thrust sleeve I is provided with multiple grooves A. The outer ring of thrust sleeve II is provided with multiple grooves. A piston ring is installed in each groove. The multiple piston rings form a labyrinth sealing structure. The air cavity pressure is P1, the pressure on the air cavity side of the bearing is P2, and the shaft is provided with a plurality of grooves A. The pressure on the bearing motor side is P3, the opening pressure of the one-way valve is P4, and the gas resistance of the labyrinth seal structure is P5. When the circulating pump starts working, the air cavity pressure P1 is higher than the pressure P3 on the bearing motor side, and the mixed gas in the air cavity enters the motor through the water-gas separator, the inner hole on the air cavity side of the rotor shaft, the one-way valve and the radial through hole of the motor rotor shaft; under the action of the centrifugal force of the water-gas separator, the liquid water entering the inner hole on the air cavity side of the rotor shaft is thrown back into the air cavity from the axial vent hole and radial vent hole of the water-gas separator.

[0007] When the dry gas entering the motor increases the pressure P3 on the bearing motor side, when the air cavity pressure P1-the bearing motor side pressure P3 is less than the one-way valve opening pressure P4, the one-way valve closes. At this time, the bearing motor side pressure P3 = the air cavity pressure P1-the one-way valve opening pressure P4.

[0008] When the one-way valve is closed, the pressure P3 on the bearing motor side is greater than the pressure P2 on the bearing air cavity side, and the airflow direction on both sides of the bearing is from the motor to the air cavity, preventing the mixed gas containing water vapor and liquid water from entering the bearing and motor from the air cavity.

[0009] The labyrinth sealing structure is configured to form resistance along the way, thereby reducing the gas pressure so that the bearing air cavity side pressure P2 is less than the air cavity pressure P1. When the gas resistance of the labyrinth sealing structure is P5, the bearing air cavity side pressure P2 = air cavity pressure P1 - labyrinth sealing structure gas resistance P5.

[0010] The motor rotor shaft is supported in the motor by bearings. The motor rotor shaft is provided with a rotor shaft motor side inner hole, a rotor shaft air cavity side inner hole and a motor rotor shaft radial through hole. A one-way valve is installed in the rotor shaft motor side inner hole, and a plug is installed at the end of the rotor shaft motor side inner hole; a water-gas separator is installed in the rotor shaft air cavity side inner hole; and the motor rotor shaft radial through hole connects the air cavity and the motor.

[0011] The water-gas separator is provided with an axial vent hole and a radial vent hole. The axial vent hole is connected to the radial vent hole. The radial vent hole is provided on the side of the one-way valve close to the motor.

[0012] The piston ring and the groove are fitted with small clearances in the axial and radial directions. The piston ring and the pump body are installed with interference fit. The piston ring and thrust sleeves I and II form a labyrinth seal structure between the air cavity 3 and the bearing.

[0013] The inner hole of the thrust sleeve I is connected to the motor rotor shaft through an interference fit, and the outer ring of the thrust sleeve I6 is a clearance fit with the pump body 1; the inner hole of the thrust sleeve II is connected to the motor rotor shaft through an interference fit, and the outer ring of the thrust sleeve II is a clearance fit with the pump body.

[0014] The piston ring end face installed in the groove of the thrust sleeve I and the inner hole of the pump body, as well as the side face of the piston ring and the side face of the groove are all clearance fit; the piston ring end face installed in the groove of the thrust sleeve II and the inner hole of the pump body, as well as the side face of the piston ring and the side face of the groove are all clearance fit.

[0015] The number of thrust sleeves is not limited to two, the number of piston rings is not limited to six, and the material of the piston rings is metal, nylon, PEEK or PTFE.

[0016] The technical solution of the present invention is adopted, and the working principle and beneficial effects are as follows:

[0017] The fuel cell hydrogen circulation pump sealing structure described in the present invention is that when the structure is set, the impeller is installed on the motor rotor shaft through an interference fit. When the motor rotor shaft rotates, it drives the impeller to rotate. The impeller is located in the air cavity. During the operation of the hydrogen circulation pump, the impeller rotates and transports hydrogen under the drive of the motor. Since the fuel cell generates electricity through the electrochemical reaction of hydrogen and oxygen, it will also produce water. After the water mixes with the excess hydrogen, it enters the air cavity through the air inlet of the hydrogen circulation pump. When the seal between the air cavity and the motor is poor, the water will pass through the air seal and enter the inside of the bearing and the inside of the motor, causing rust and damage to the bearing and the inside of the motor. In response to the above technical problems, the present invention achieves sealing and waterproofing functions from two aspects: first, a labyrinth seal structure is formed by using the small gap between the thrust sleeve and the piston ring. The labyrinth seal structure prevents most water from entering the motor side from the air cavity on the one hand, and reduces the pressure of gas flowing into the motor side from the air cavity on the other hand; second, the pressure of the motor cavity is increased by using the through hole connecting the motor rotor shaft and the air cavity, and the pressure difference between the air cavity and the motor is controlled by the opening pressure of the one-way valve. The centrifugal force generated by the water-gas separator under the action of high-speed rotation is used to throw out liquid water, preventing water from entering the motor and preventing the bearings and the motor from rusting and damaging. When the circulating pump starts working, the air cavity pressure P1 is higher than the pressure P3 on the motor side of the bearing, and the mixed gas in the air cavity enters the interior of the motor through the water-gas separator, the inner hole on the air cavity side of the rotor shaft, the one-way valve and the radial through hole of the motor rotor shaft; under the action of the centrifugal force of the water-gas separator, the liquid water entering the inner hole on the air cavity side of the rotor shaft is thrown back into the air cavity through the axial vent B and radial vent C of the water-gas separator. That is to say, when the pressure on the motor side is greater than the pressure on the air cavity side, the pressure difference prevents the gas containing water vapor from flowing from the air cavity side to the motor side, thereby achieving waterproofing of the bearings and motor and improving the life of the bearings and motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following is a brief description of the contents and symbols in the drawings of this specification:

[0019] Figure 1 This is a schematic structural diagram of the sealing structure of the fuel cell hydrogen circulation pump according to the present invention;

[0020] Figure 2 This is a structural schematic diagram of the thrust sleeve of the sealing structure of the fuel cell hydrogen circulation pump according to the present invention;

[0021] Figure 3 This is a structural schematic diagram of the water-gas separator of the fuel cell hydrogen circulation pump sealing structure of the present invention;

[0022] Figure 4 This is a schematic cross-sectional view of the water-gas separator of the sealing structure of the fuel cell hydrogen circulation pump according to the present invention;

[0023] The numbers in the accompanying drawings are: 1, pump body; 2, cover plate; 3, air cavity; 4, motor; 5, motor rotor shaft; 6, thrust sleeve I; 7, thrust sleeve II; 8, piston ring; 9, inner hole of rotor shaft on the motor side; 10, one-way valve; 11, plug; 12, inner hole of rotor shaft on the air cavity side; 13, water-gas separator; 14, radial through hole of motor rotor shaft; 15, impeller; 16, bearing;

[0024] A. Groove; B. Axial vent hole of water-gas separator; C. Radial vent hole of water-gas separator;

[0025] P1: air cavity pressure; P2: bearing air cavity side pressure; P3: bearing motor side pressure (motor pressure); P4: one-way valve opening pressure; P5: labyrinth seal structure gas resistance. DETAILED DESCRIPTION

[0026] The following describes the embodiments with reference to the accompanying drawings to further explain in detail the specific embodiments of the present invention, such as the shapes, structures, mutual positions and connection relationships between the various components involved, the functions and working principles of the various components.

[0027] As attached Figure 1 -Attached Figure 4As shown, the present invention is a sealing structure for a fuel cell hydrogen circulation pump. An air cavity 3 is formed between one side of the pump body 1 of the circulation pump and the cover plate 2. A motor 4 is installed on the other side of the pump body 1. An impeller 15 is installed at one end of the motor rotor shaft 5 of the motor 4 extending into the air cavity 3. A thrust sleeve I6 and a thrust sleeve II7 are installed between the motor rotor shaft 5 and the pump body 1. A plurality of grooves A are provided on the outer ring of the thrust sleeve I6. A plurality of grooves A are provided on the outer ring of the thrust sleeve II7. A piston ring 8 is installed in each groove A. The multiple piston rings 8 form a labyrinth sealing structure. The air cavity pressure is P1, and the pressure on the bearing air cavity side is P 2, the bearing motor side pressure is P3, the one-way valve opening pressure is P4, and the labyrinth seal structure gas resistance is P5. When the circulating pump starts operating, the air chamber pressure P1 is higher than the bearing motor side pressure P3. The mixed gas in air chamber 3 enters the interior of motor 4 through water-gas separator 13, rotor shaft air chamber side inner hole 12, one-way valve 10, and motor rotor shaft radial through hole 14. Under the centrifugal force of the water-gas separator, liquid water entering the rotor shaft air chamber side inner hole 12 is flung back into air chamber 3 through the water-gas separator axial vent B and water-gas separator radial vent C of water-gas separator 13. The above structure addresses the shortcomings of the existing technology and proposes an improved technical solution. During the structural setting, the impeller 15 is installed on the motor rotor shaft 5 through an interference fit. When the motor rotor shaft 5 rotates, it drives the impeller 15 to rotate. The impeller 15 is located in the air cavity 3. During the operation of the hydrogen circulation pump, the impeller 15 rotates and transports hydrogen under the drive of the motor. Since the fuel cell generates electricity through the electrochemical reaction of hydrogen and oxygen, water is also produced. After the water is mixed with the excess hydrogen, it enters the air cavity 3 through the air inlet of the hydrogen circulation pump. When the seal between the air cavity 3 and the motor 4 is poor, the water will pass through the air seal and enter the inside of the bearing 16 and the inside of the motor 4, causing rust and damage to the bearing 16 and the inside of the motor 4. In response to the above technical problems, the present invention realizes the sealing and waterproofing functions from two aspects: first, a labyrinth sealing structure is formed by utilizing the small gap between the thrust sleeve and the piston ring 8. The labyrinth sealing structure prevents most of the water from entering the motor 4 side from the air cavity 3 on the one hand, and reduces the pressure of the gas flowing from the air cavity 3 side to the motor 4 side on the other hand; secondly, the through hole connecting the motor rotor shaft 5 and the air cavity 3 is utilized to increase the pressure in the inner cavity of the motor, and the opening pressure of the one-way valve 10 is utilized to control the pressure difference between the air cavity 3 and the motor 4, and the centrifugal force generated by the water-gas separator 13 under the action of high-speed rotation is utilized to throw out the liquid water, thereby preventing water from entering the motor 4 and preventing the bearings and the inside of the motor from rusting and being damaged. When the circulating pump starts working, the air cavity pressure P1 is higher than the bearing motor side pressure P3, and the mixed gas in the air cavity 3 enters the interior of the motor 4 through the water-gas separator 13, the rotor shaft air cavity side inner hole 12, the one-way valve 10 and the motor rotor shaft radial through hole 14; under the action of the centrifugal force of the water-gas separator, the liquid water entering the rotor shaft air cavity side inner hole 12 is thrown back to the air cavity 3 from the water-gas separator axial vent B and the water-gas separator radial vent C of the water-gas separator 13.That is, when the pressure on the motor side is greater than the pressure on the air cavity side, the pressure differential prevents water-laden gas from flowing from the air cavity side to the motor side, waterproofing the bearings and motor and improving their lifespan. The fuel cell hydrogen circulation pump sealing structure of the present invention has a simple structure. Its combination of labyrinth sealing and pressure control improves the sealing effect, preventing water from entering the bearings and motor, extending the service life of the circulation pump, and reducing sealing and maintenance costs.

[0028] When the dry gas entering the motor 4 increases the pressure P3 on the bearing motor side, when the air cavity pressure P1-the bearing motor side pressure P3 is less than the one-way valve opening pressure P4, the one-way valve 10 is closed, and the gas in the air cavity 3 cannot enter the motor 4. At this time, the bearing motor side pressure P3 = the air cavity pressure P1-the one-way valve opening pressure P4. The above structure, in the above state, achieves gas isolation, and the gas cannot enter the motor. When the one-way valve 10 is closed, the bearing motor side pressure P3 is greater than the bearing air cavity side pressure P2, and the airflow direction on both sides of the bearing is from the motor 4 to the air cavity 3, preventing the mixed gas containing water vapor and liquid water from entering the bearing 16 and the motor 4 from the air cavity 3. The above structure effectively prevents water vapor and liquid water from entering through the pressure difference.

[0029] The labyrinth sealing structure is configured to form resistance along the way, thereby reducing the gas pressure so that the bearing air cavity side pressure P2 is less than the air cavity pressure P1. When the gas resistance of the labyrinth sealing structure is P5, the bearing air cavity side pressure P2 = air cavity pressure P1 - labyrinth sealing structure gas resistance P5.

[0030] The motor rotor shaft 5 is supported within the motor 4 by bearings 16. The motor rotor shaft 5 is provided with a rotor shaft motor-side inner hole 9, a rotor shaft air cavity-side inner hole 12, and a motor rotor shaft radial through hole 14. A check valve 10 is installed within the rotor shaft motor-side inner hole 9, and a plug 11 is installed at the end of the rotor shaft motor-side inner hole 9. A moisture separator 13 is installed within the rotor shaft air cavity-side inner hole 12. The motor rotor shaft radial through hole 14 connects the air cavity 3 and the motor 4. In the above structure, the motor rotor shaft 5 is a hollow shaft, forming the rotor shaft motor-side inner hole 9. A check valve 10 is installed within the rotor shaft motor-side inner hole 9, and a plug 11 is installed at the end of the rotor shaft motor-side inner hole 9. A moisture separator 13 is installed at the end of the air cavity-side inner hole. The motor rotor shaft 5 is provided with a motor rotor shaft radial through hole 14, which connects the air cavity 3 and the motor 4. The check valve controls the direction of airflow. When the check valve 10 is open, airflow flows from the air cavity side to the motor side. The water-gas separator 13 is connected to the motor rotor shaft 5 via a thread, and the direction of rotation of the thread is opposite to the direction of rotation of the motor rotor shaft 5 .

[0031] The water-gas separator 13 is provided with a water-gas separator axial vent B and a water-gas separator radial vent C. The water-gas separator axial vent B is connected to the water-gas separator radial vent C, and the water-gas separator radial vent C is provided on the side of the one-way valve 10 close to the motor 4. With the above structure, when the circulating pump starts working, the air cavity pressure P1 is higher than the pressure P3 on the bearing motor side. The mixed gas in the air cavity 3 enters the interior of the motor 4 through the water-gas separator 13, the rotor shaft air cavity side inner hole 12, the one-way valve 10, and the motor rotor shaft radial through hole 14. Under the action of the centrifugal force of the water-gas separator, the liquid water entering the rotor shaft air cavity side inner hole 12 is flung back into the air cavity 3 through the water-gas separator axial vent B and the water-gas separator radial vent C of the water-gas separator 13, thereby achieving waterproofing.

[0032] The piston ring 8 has a small clearance fit with the groove A in both the axial and radial directions. The piston ring 8 is installed with the pump body 1 using an interference fit. The piston ring 8 and the thrust sleeves I6 and II7 form a labyrinth seal structure between the air cavity 3 and the bearing 16. In this structure, the piston ring and the thrust sleeve are reliably connected, and the piston ring is clamped in the groove to form a labyrinth seal structure.

[0033] The inner hole of the thrust sleeve I6 is connected to the motor rotor shaft 5 through an interference fit, and the outer ring of the thrust sleeve I6 is a clearance fit with the pump body 1; the inner hole of the thrust sleeve II7 is connected to the motor rotor shaft 5 through an interference fit, and the outer ring of the thrust sleeve II7 is a clearance fit with the pump body 1.

[0034] A clearance fit is provided between the end face of the piston ring 8 mounted in groove A of the thrust sleeve I6 and the inner bore of the pump body 1, as well as between the side faces of the piston ring 8 and the side faces of the groove A. A clearance fit is provided between the end face of the piston ring 8 mounted in groove A of the thrust sleeve II7 and the inner bore of the pump body 1, as well as between the side faces of the piston ring 8 and the side faces of the groove A. The number of thrust sleeves is not limited to two, and the number of piston rings 8 is not limited to six. The piston rings 8 are made of nylon, PEEK, or PTFE, offering excellent wear resistance and long service life.

[0035] In the sealing structure of the fuel cell hydrogen circulation pump described in the present invention, the impeller 15 is installed on the motor rotor shaft 5 by an interference fit. When the motor rotor shaft 5 rotates, it drives the impeller 15 to rotate, and the impeller 15 is located in the air cavity 3. During the operation of the hydrogen circulation pump, the impeller 15 rotates and transports hydrogen under the drive of the motor; because the fuel cell generates electricity through the electrochemical reaction of hydrogen and oxygen, it will also produce water. After the water is mixed with the excess hydrogen, it enters the air cavity 3 through the air inlet of the hydrogen circulation pump. When the seal between the air cavity 3 and the motor 4 is poor, the water will pass through the air seal and enter the interior of the bearing 16 and the interior of the motor 4, causing rust and damage to the bearing 16 and the interior of the motor 4. In response to the above technical problems, the sealing and waterproof functions are achieved from two aspects: first, the small gap between the thrust sleeve and the piston ring 8 is used to form a labyrinth sealing structure. On the one hand, the labyrinth sealing structure prevents most of the water from entering the motor 4 side from the air cavity 3, and on the other hand, reduces the gas pressure flowing from the air cavity 3 side to the motor 4 side; secondly, the through hole connecting the motor rotor shaft 5 and the air cavity 3 is used to increase the pressure in the motor cavity, and the opening pressure of the one-way valve 10 is used to control the pressure difference between the air cavity 3 and the motor 4, and the centrifugal force generated by the water-gas separator 13 under the action of high-speed rotation is used to throw out the liquid water, thereby preventing water from entering the motor 4 and preventing the bearings and the inside of the motor from rusting and damage. When the circulating pump begins operating, the air chamber pressure P1 is higher than the pressure P3 on the bearing motor side. The mixed gas in air chamber 3 enters motor 4 through water-gas separator 13, rotor shaft air chamber inner hole 12, one-way valve 10, and motor rotor shaft radial through-hole 14. Under the centrifugal force of the water-gas separator, liquid water that enters rotor shaft air chamber inner hole 12 is flung back into air chamber 3 through water-gas separator axial vent B and water-gas separator radial vent C in water-gas separator 13. In other words, when the motor-side pressure is greater than the air chamber pressure, the pressure differential prevents water-laden gas from flowing from the air chamber side into the motor side, waterproofing the bearing and motor and improving their lifespan.

[0036] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A fuel cell hydrogen circulation pump sealing structure, characterized by: An air cavity (3) is formed between one side of the pump body (1) and the cover plate (2) of the circulation pump, and a motor (4) is installed on the other side of the pump body (1). An impeller (15) is installed at one end of the motor rotor shaft (5) of the motor (4) extending into the air cavity (3). A thrust sleeve I (6) and a thrust sleeve II (7) are installed between the motor rotor shaft (5) and the pump body (1). A plurality of grooves (A) are provided on the outer ring of the thrust sleeve I (6), and a plurality of grooves (A) are provided on the outer ring of the thrust sleeve II (7). A piston ring (8) is installed in each groove (A). The plurality of piston rings (8) form a labyrinth seal structure. The air cavity pressure is P1, the bearing air cavity side pressure is P2, and the shaft The pressure on the bearing motor side is P3, the opening pressure of the one-way valve is P4, and the gas resistance of the labyrinth seal structure is P5. When the circulating pump starts working, the air cavity pressure P1 is higher than the pressure P3 on the bearing motor side, and the mixed gas in the air cavity (3) enters the interior of the motor (4) through the water-gas separator (13), the inner hole (12) on the air cavity side of the rotor shaft, the one-way valve (10), and the radial through hole (14) on the motor rotor shaft; under the centrifugal force of the water-gas separator, the liquid water entering the inner hole (12) on the air cavity side of the rotor shaft is thrown back to the air cavity (3) from the water-gas separator axial vent (B) and the water-gas separator radial vent (C) of the water-gas separator (13); When the gas resistance P5 of the labyrinth seal structure is greater than the one-way valve opening pressure P4, the pressure P3 on the bearing motor side is greater than the pressure P2 on the bearing air cavity side, and the air flow direction on both sides of the bearing is from the motor (4) to the air cavity (3), preventing the mixed gas containing water vapor and liquid water from entering the bearing (16) and the motor (4) from the air cavity (3); The labyrinth sealing structure is configured to form resistance along the way, thereby reducing the gas pressure so that the bearing air cavity side pressure P2 is less than the air cavity pressure P1. When the gas resistance of the labyrinth sealing structure is P5, the bearing air cavity side pressure P2 = air cavity pressure P1 - labyrinth sealing structure gas resistance P5.

2. The fuel cell hydrogen circulation pump sealing structure according to claim 1, characterized in that: When the dry gas entering the motor (4) increases the pressure P3 on the bearing motor side, when the air cavity pressure P1-the bearing motor side pressure P3 is less than the one-way valve opening pressure P4, the one-way valve (10) is closed, and the gas in the air cavity (3) cannot enter the motor (4). At this time, the bearing motor side pressure P3 = the air cavity pressure P1-the one-way valve opening pressure P4.

3. The fuel cell hydrogen circulation pump sealing structure according to claim 1 or 2, characterized in that: The motor rotor shaft (5) is supported in the motor (4) by a bearing (16). The motor rotor shaft (5) is provided with a rotor shaft motor side inner hole (9), a rotor shaft air cavity side inner hole (12) and a motor rotor shaft radial through hole (14). A one-way valve (10) is installed in the rotor shaft motor side inner hole (9), and a plug (11) is installed at the end of the rotor shaft motor side inner hole (9); a water-gas separator (13) is installed in the rotor shaft air cavity side inner hole (12); and the motor rotor shaft radial through hole (14) communicates with the air cavity (3) and the motor (4).

4. The fuel cell hydrogen circulation pump sealing structure according to claim 1, characterized in that: The water-gas separator (13) is provided with a water-gas separator axial vent (B) and a water-gas separator radial vent (C), the water-gas separator axial vent (B) is connected to the water-gas separator radial vent (C), and the water-gas separator radial vent (C) is provided on the side of the one-way valve (10) close to the motor (4).

5. The fuel cell hydrogen circulation pump sealing structure according to claim 1 or 2, characterized in that: The piston ring (8) and the groove (A) are fitted with a small clearance in both the axial and radial directions. The piston ring (8) and the pump body (1) are installed with an interference fit. The piston ring (8) and the thrust sleeve I (6) and the thrust sleeve II (7) form a labyrinth seal structure between the air cavity (3) and the bearing (16).

6. The fuel cell hydrogen circulation pump sealing structure according to claim 5, characterized in that: The inner hole of the thrust sleeve I (6) is connected to the motor rotor shaft (5) through an interference fit, and the outer ring of the thrust sleeve I (6) is clearance fit with the pump body (1); the inner hole of the thrust sleeve II (7) is connected to the motor rotor shaft (5) through an interference fit, and the outer ring of the thrust sleeve II (7) is clearance fit with the pump body (1).

7. The fuel cell hydrogen circulation pump sealing structure according to claim 1 or 2, characterized in that: There is a clearance fit between the end face of the piston ring (8) installed in the groove (A) of the thrust sleeve I (6) and the inner hole of the pump body (1), and between the side face of the piston ring (8) and the side face of the groove (A); there is a clearance fit between the end face of the piston ring (8) installed in the groove (A) of the thrust sleeve II (7) and the inner hole of the pump body (1), and between the side face of the piston ring (8) and the side face of the groove (A).

8. The fuel cell hydrogen circulation pump sealing structure according to claim 1 or 2, characterized in that: The number of thrust sleeves is not limited to two, the number of piston rings (8) is not limited to six, and the material of the piston rings (8) is metal, nylon, PEEK, or PTFE.

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