A motor for a cryogenic pump with a parallel liquid cooling structure

Abstract

The present invention relates to a low-temperature pump motor with a parallel liquid cooling structure, comprising a stator assembly, a rotor assembly, a casing, and a pump body outside the motor, and also comprising a stator cooling system and a rotor cooling system. The stator cooling system comprises axial cooling and radial cooling, wherein the axial cooling utilizes the low-temperature medium flowing through the liquid guide channel for cooling, and the radial cooling utilizes the low-temperature medium in the stator pressure plate cavity for cooling. The rotor cooling system utilizes the low-temperature medium flowing through the rotating shaft and the central axis of the rotor core for cooling. Compared with the prior art, the cooling method of the present invention does not require the aid of an external cooling system, does not require the consumption of cooling medium and the recycling of cooling medium, and only requires the use of part of the low-temperature medium in the pump for cooling. As a low-temperature pump motor, the liquid guide channel unique to the stator assembly will increase the flow rate. Due to the different characteristics of different low-temperature media, the cooling method of the present invention ensures that the low-temperature medium does not flow through the interior of the motor while ensuring the sealing of the motor.

Description

Technical Field

[0001] The present invention relates to a motor cooling structure, in particular to a permanent magnet motor for a cryogenic pump with a parallel liquid cooling structure, belonging to the technical field of electrical engineering. Background Art

[0002] Submersible cryogenic pumps are often used to transport various cryogenic liquid media, and the motor is usually immersed in the cryogenic liquid. The stable operation of the motor determines the transportation efficiency of the submersible pump.

[0003] Submersible cryogenic pump motors must ensure absolute sealing during operation, so cooling methods commonly used in traditional motors, such as air cooling, water cooling, and oil cooling, are not suitable. Excessive temperature rise will also lead to the vaporization of the cryogenic medium, causing cavitation. In response to the problem of excessive internal temperature rise in cryogenic pump motors, the present invention proposes a cryogenic pump motor with a parallel liquid cooling structure. Unlike traditional cooling methods, the cooling method of the present invention does not require the cooling medium to enter the air gap of the motor, and there is no need to consider the consumption and recovery of the cooling medium, thereby ensuring the sealing and safety of the motor during operation. Summary of the Invention

[0004] A low-temperature pump motor with a parallel liquid cooling structure includes a casing, a stator assembly, and a rotor assembly. The stator assembly is fixed to the inner wall of the casing and includes a stator core, a stator pressure plate, and a winding. The stator pressure plate is fixed to both ends of the stator core. The rotor assembly is located inside the stator assembly and includes bearings, a rotating shaft, a rotor core, and a permanent magnet. The rotating shaft is mounted on the end covers on both sides of the casing through bearings.

[0005] A main flow channel is formed between the casing and the pump body. The bottom of the pump body is a fluid inlet, and the upper part is a fluid outlet. Both the fluid inlet and the outlet are communicated with the main flow channel.

[0006] The stator core and the stator pressure plates on both sides have axial openings forming a first liquid guide channel, which is used for axial cooling of the stator to solve the problems of flow resistance and cooling efficiency of the low-temperature medium. In order not to affect the magnetic flux distribution of the stator yoke, the opening is as far away from the winding as possible and is set at the angle between the two stator slots. The liquid guide holes are concentrically distributed circumferentially with the stator, and the number is equal to the number of stator slots. The center of the liquid guide hole and the center of the two stator slots form an isosceles triangle, and the radius of the liquid guide hole is half the radius of the stator slot.

[0007] The stator radial cooling system includes a liquid inlet, a liquid outlet, and a stator pressure plate cavity. The stator pressure plate is located on both sides of the stator core. The stator pressure plate is made into a cavity shape. On the one hand, it plays a role in pressing the stator silicon steel sheet. On the other hand, the low-temperature medium in the pressure plate cavity plays a role in reducing the temperature of the stator core.

[0008] The rotating shaft and the rotor core are opened along the central axial direction to form a second liquid guide channel, and the inner wall of the second liquid guide channel is smooth and flat to ensure that the liquid can flow through completely when the rotor rotates at high speed.

[0009] Furthermore: sealing covers are installed on both sides of the stator pressure plate, and a closed air space is formed between the stator, the sealing cover and the rotor. Due to the different properties of various low-temperature media, the sealing cover is set to prevent the low-temperature medium in the pump from flowing into the pump. The outer surface of the sealing cover is in direct contact with the low-temperature medium, which effectively reduces the temperature of the closed air space.

[0010] Furthermore, a small amount of low-temperature medium flows into the motor, and the low-temperature medium in the areas on both sides of the bearing can play a role in lubricating the bearing and reducing the bearing temperature.

[0011] Furthermore, the inner wall of the first liquid guiding channel is shaped as a Tesla valve structure to ensure unidirectional flow of the cryogenic medium and increase the cooling area.

[0012] Furthermore: the motor housing at the fluid inlet and outlet is made into different streamlined shapes according to the fluid speed, with the aim of reducing the resistance of the housing to the liquid. The shape of the pump body is as close as possible to the shape of the motor housing, so that the main flow channel between the two is as round and smooth as possible to reduce the resistance to liquid flow.

[0013] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a cryopump motor with a parallel liquid cooling structure. By adopting a parallel cooling structure for the motor stator and rotor, the motor's cooling efficiency is effectively improved. Compared with the prior art, the present invention has the following advantages:

[0014] 1. The present invention uses a low-temperature medium to cool both the stator and rotor assemblies of the motor. The ultra-low-temperature medium can effectively reduce the temperature without the need for additional equipment. Compared with the traditional single stator cooling method, the stator and rotor parallel liquid cooling structure can effectively reduce the internal temperature of the motor and improve the cooling efficiency.

[0015] 2. Low-temperature medium can lubricate and cool the bearings, so there is no need to add bearing cooling devices, which improves bearing reliability.

[0016] 3. After cooling, the low-temperature medium does not need to be equipped with a discharge device and flows out of the pump directly.

[0017] 4. The liquid-conducting channel used in the present invention can not only reduce the temperature but also increase the flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a cross-sectional view of a low-temperature pump motor with a parallel liquid cooling structure according to the present invention.

[0019] Figure 2This is a cross-sectional view of the stator core pressure plate, including the first liquid guide channel.

[0020] Figure 3 It is the stator pressure plate cavity structure.

[0021] Figure 4 Tesla valve structure used for the first liquid-conducting channel.

[0022] In the figure: 1-pump body, 2-1-bottom inlet of pump body, 2-2-upper outlet of pump body, 3-main channel, 4-casing, 5-1-bottom inlet of casing, 5-2-upper outlet of casing, 6-rotor core, 7-rotating shaft, 8-second liquid guide channel, 9-bearing, 10-1-inlet of bottom end cover of casing, 10-2-outlet of upper end cover of casing, 11-sealing cover, 12-stator core, 13-stator pressure plate, 14-first liquid guide channel, 15-sealed air gap, 16-liquid guide hole of first liquid guide channel, 17-pressure plate inlet, 18-cavity in pressure plate, 19-square liquid storage tank, 20-Tesla valve structure.

Claims

1. A low-temperature pump motor with a parallel liquid cooling structure, comprising a housing (4), a stator assembly, and a rotor assembly, wherein the stator assembly is fixed on the inner side wall of the housing and comprises a stator core (12), a stator pressure plate (13), and a winding, the stator pressure plate being fixed at both ends of the stator core, the rotor assembly being located inside the stator assembly and comprising a bearing (9), a rotating shaft (7), a rotor core (6), and a permanent magnet, the rotating shaft being mounted on both side end covers of the housing through bearings; a main flow channel (3) is formed between the housing (4) and the pump body (1), the bottom of the pump body is a fluid inlet (2-1), and the upper part is a fluid outlet (2-2), and the fluid inlet and outlet are both connected to the main flow channel; the stator core (12) and the stator pressure plates (13) on both sides are axially opened to form a first liquid guide channel (14), which is used for axial cooling of the stator to solve the flow resistance and cooling efficiency of the low-temperature medium. The invention relates to a problem that in order not to affect the magnetic flux distribution of the stator yoke, the opening position is far away from the winding and is set at the angle between the two stator slots. The liquid guide holes (16) are distributed circumferentially concentrically with the stator and the number is equal to the number of stator slots. The center of the liquid guide hole and the center of the two stator slots form an isosceles triangle, and the radius of the liquid guide hole is half of the radius of the stator slot. The stator radial cooling includes a liquid inlet, a liquid outlet and a stator pressure plate cavity (18). The stator pressure plate (13) is located on both sides of the stator core (12). The stator pressure plate is made into a cavity shape. On the one hand, it plays a role in pressing the stator silicon steel sheet. On the other hand, the low-temperature medium in the pressure plate cavity plays a role in reducing the temperature of the stator core. The rotating shaft (7) and the rotor core (6) are opened along the central axial direction to form a second liquid guide channel (8). The inner wall of the second liquid guide channel is smooth and flat to ensure that the liquid can flow completely when the rotor rotates at high speed.

2. The cryopump motor with a parallel liquid cooling structure according to claim 1, characterized in that: Sealing covers (11) are installed on both sides of the stator pressure plate (13), and a closed air space (15) is formed between the stator, the sealing cover and the rotor. Due to the different properties of various low-temperature media, the sealing cover is provided to prevent the low-temperature media in the pump from flowing in. The outer surface of the sealing cover is in direct contact with the low-temperature media, which effectively reduces the temperature of the closed air space.

3. The cryopump motor with a parallel liquid cooling structure according to claim 1, characterized in that: A small amount of low-temperature medium flows into the motor, and the low-temperature medium in the areas on both sides of the bearing (9) can play a role in lubricating the bearing and reducing the bearing temperature.

4. The cryopump motor with a parallel liquid cooling structure according to claim 1, characterized in that: The inner wall shape of the first liquid guiding channel is set to a Tesla valve structure (20), which ensures the unidirectional flow of the low-temperature medium and increases the cooling area.

5. The cryopump motor with a parallel liquid cooling structure according to claim 1, characterized in that: The motor housings at the fluid inlet (2-1) and outlet (2-2) are made into different streamlined shapes according to the fluid speed, in order to reduce the resistance of the housing to the liquid. The shape of the pump body fits the shape of the motor housing, making the main flow channel between the two round and smooth to reduce the resistance to liquid flow.

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