A kind of global ultrafast cryogenic cooling shield motor structure

Abstract

The application discloses a kind of all-domain ultrafast cryogenic cooling shield motor structure, belong to the technical field of power generation, power transformation or power distribution.The structure includes stator and rotor assembly, for separating as stator cooling zone, rotor gap cooling zone, air gap cooling zone The stator / rotor shield sleeve adopts multistage cooling mode of low-temperature gaseous nitrogen precooling, liquid nitrogen deep cooling.Stator side is provided with core micropore, slot insulation framework, coil embedded cooling pipe, rotor side is provided with cooling channel formed by permanent magnet and sheath, cooling channel between permanent magnet and sheath and hollow shaft cooling channel, form all-domain built-in cooling flow channel combination.System is equipped with multistage partition medium supply system, realizes two kinds of working modes of shutdown precooling, on-load operation cooling.The heat exchange path of the application covers the core components of motor, cooling rate is fast, temperature is uniform, can effectively avoid large temperature difference stress damage, can meet the demand of low-temperature shield motor ultrafast cryogenic and long-term operation working condition.

Description

Technical Field

[0001] This invention relates to cryogenic motor cooling technology, specifically disclosing a full-range ultra-rapid deep-cryogenic cooling shielded motor structure, particularly a cryogenic shielded motor for aerospace systems, belonging to the technical field of power generation, power transformation or power distribution. Background Technology

[0002] The shielded motors and cryogenic pumps that power aerospace liquid oxygen and liquid methane propulsion systems need to operate stably in a deep cryogenic environment of -196℃, which places stringent requirements on the motor's cooling capacity, temperature field uniformity, and structural resistance to cryogenic stress.

[0003] Existing cryogenic shielded motor cooling solutions mostly employ external chamber purging, overall medium immersion, and cooling via outer casing jackets, which have several significant drawbacks: First, the cooling path is singular, relying solely on heat exchange with the external environment. Core heat-generating and temperature-bearing components such as stator windings, slot insulation, rotor permanent magnets, and shafts cannot be specifically cooled, resulting in low overall heat exchange efficiency and a long time required to drop from room temperature to -196℃, making it difficult to meet the requirements of rapid cooling tests and quick start-up conditions. Second, the medium used is crude; most solutions directly introduce liquid nitrogen for rapid cooling. The temperature difference between the motor's room temperature and -196℃ liquid nitrogen exceeds 200℃, easily generating huge thermal stress in components such as the stator core, slot insulation, windings, surface-mounted permanent magnets, and rotor sheaths. This leads to several problems: First, insulation layer brittleness, permanent magnet demagnetization failure, and structural deformation. Second, some solutions using only low-temperature nitrogen cooling cannot achieve the target deep cryogenic temperature of -196℃. Third, the cooling channel layout is unreasonable; traditional flow channels are mostly externally arranged without being integrated with the motor insulation structure and rotor body for unified design, resulting in a loose structure, cumbersome assembly, and uneven temperature distribution, with prominent problems of local overcooling and insufficient heat exchange in the motor. Fourth, most existing cooling structures only support cooling when the motor is stopped, and cannot simulate the working mode of the motor running and being deeply cooled simultaneously in actual working conditions, resulting in a large deviation between test data and the actual service state of the equipment. Fifth, the low-temperature exhaust gas after heat exchange is directly discharged, resulting in serious waste of cooling capacity and high overall energy consumption of the equipment.

[0004] Currently available technologies, while exhibiting scattered designs such as external partitioned cooling of the motor, single gas-liquid two-stage cooling, and simplified rotor flow channels, have not formed an integrated structure encompassing multi-level internal flow channels in the stator, integrated slot insulation and cooling channels, three independent cooling channels in the rotor, low-temperature nitrogen gradient pre-cooling + liquid nitrogen deep cooling, synchronous cooling under load, and closed-loop recovery of cold energy. Furthermore, no targeted optimization has been made for the specific operating conditions of liquid oxygen and liquid methane cryogenic media pumps. Therefore, a completely new cooling structure is urgently needed to meet the multiple requirements of rapid cooling, uniform temperature field, structural protection, realistic operating conditions, and energy saving. Summary of the Invention

[0005] This invention addresses the shortcomings of existing low-temperature shielded motor cooling structures, such as slow cooling rate, single cooling path, inability to cool under load, easy component damage from rapid cooling at low temperatures, unreasonable flow channel layout, and low cooling capacity utilization. It provides a shielded motor structure with full-area ultra-rapid deep cooling, which features multiple independent built-in cooling channels throughout the motor stator and rotor. It adopts a two-stage medium cooling process of low-temperature gaseous nitrogen gradient pre-cooling and liquid nitrogen deep cooling, which achieves ultra-rapid deep cooling of the low-temperature shielded motor while effectively avoiding structural and insulation damage caused by large temperature differences.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] A full-range high-speed deep cryogenic cooling shielded motor structure includes: a housing, a stator, and a rotor sleeved on a rotating shaft. A rotor shielding sleeve is sleeved on the outside of the rotor, and a stator shielding sleeve is sleeved inside the stator. The stator shielding sleeve is sleeved on the outside of the rotor shielding sleeve. The cooling channels opened on the stator and the cooling channels inside the housing form a full-range built-in cooling channel for the stator cooling area. The cooling channels opened on the rotor and the cooling passages inside the rotating shaft form a cooling channel for the rotor gap cooling area. The gap between the stator shielding sleeve and the rotor shielding sleeve forms an air gap cooling area channel.

[0008] The method for rapid cryogenic cooling of the entire shielded motor structure is as follows: First, the stator cooling area, rotor gap cooling area, and air gap cooling area are pre-cooled with low-temperature gaseous nitrogen until the overall temperature reaches the pre-cooling threshold that meets the requirements for insulation and low-temperature protection of permanent magnets. Then, according to the principle of prioritizing the reduction of stator temperature, the stator cooling area, rotor gap cooling area, and air gap cooling area are gradually cryogenically cooled with liquid nitrogen until the overall temperature reaches the target deep low temperature.

[0009] As a further optimization of the full-domain ultra-fast deep cryogenic cooling shielded motor structure, the cooling channels opened on the stator include: n sets of parallel grid-shaped cooling channels, micro-through-hole cooling channels, internal cooling channels of slot insulation, and internal cooling channels of conductors; the n sets of parallel grid-shaped cooling channels are opened on the outer surface of the stator core, where n is the number of stator slots; the micro-through-hole cooling channels are drilled on the wall surface where the stator core teeth contact the stator slot insulation skeleton; the internal cooling channels of slot insulation are cooling channels opened along the axial direction of the stator slot insulation skeleton; and the internal cooling channels of conductors are liquid nitrogen cooling pipes pre-embedded in the winding coils wound on the stator core.

[0010] As a further optimization of the full-range ultra-fast deep cooling shielded motor structure, the first cooling passage and the second cooling passage are respectively processed at intervals on the two end plates of the stator. The first cooling passage and the second cooling passage processed on the two end plates of the stator, together with the internal cooling passage of the slot insulation and the micro through hole cooling passage, form a stator hot and cold counterflow path.

[0011] As a further optimization of the full-domain ultra-fast deep cooling shielded motor structure, the positions of the first cooling path and the second cooling path correspond one-to-one with the stator slot and the slot insulation skeleton installed in the slot. The small through-hole cooling path on the periphery of one end of the internal cooling path of the slot insulation is connected to the parallel grid-shaped cooling path through the first cooling path on one side of the stator end plate, and the other end of the internal cooling path of the slot insulation is connected to the second cooling path on the other side of the stator end plate.

[0012] As a further optimization of the full-range ultra-fast deep cryogenic cooling shielded motor structure, the cooling channels opened on the rotor include: a cooling path on the surface of the permanent magnet formed between the shaping gap between adjacent permanent magnets and the inner surface of the rotor shield sleeve, and a cooling path on the surface of the rotor core formed between the groove reserved on the outer circular surface of the rotor core and the inner surface of the permanent magnet.

[0013] As a further optimization of the shielded motor structure for full-range rapid cryogenic cooling, the shielded motor structure operates in shutdown pre-cooling mode:

[0014] First, keep the motor powered off and continuously introduce low-temperature gaseous nitrogen into the micro-through-hole cooling channel, the parallel grid cooling channel, the internal cooling channel of the housing, the internal cooling channel of the slot insulation, and the internal cooling channel of the conductor, and introduce low-temperature gaseous nitrogen into the cooling channel of the permanent magnet surface, the cooling channel of the rotor core surface, and the internal cooling channel of the shaft until the temperature of the whole machine reaches the pre-cooling threshold that meets the requirements of insulation and low-temperature protection of permanent magnets.

[0015] Then, cryogenic liquid nitrogen is introduced into the cooling channels inside the conductors, the parallel grid cooling channels, and the cooling channels inside the casing. Cryogenic liquid nitrogen is also introduced into the cooling channels inside the slot insulation, the cooling channels on the surface of the permanent magnets, the cooling channels on the surface of the rotor core, and the cooling channels inside the shaft. Cryogenic liquid nitrogen is introduced into the air gap cooling zone until the overall temperature of the machine reaches the target deep cryogenic temperature.

[0016] As a further optimization of the shielded motor structure for full-range rapid cryogenic cooling, the shielded motor structure operates in a load-bearing cooling mode as follows:

[0017] First, low-temperature gaseous nitrogen is introduced into the stator cooling zone, rotor gap cooling zone, and air gap cooling zone until the overall machine temperature reaches the pre-cooling threshold for load operation. Then, the motor is instructed to run under load, and low-temperature gaseous nitrogen is introduced into the stator cooling zone, rotor gap cooling zone, and air gap cooling zone until the overall machine temperature reaches the pre-cooling threshold that meets the requirements for insulation and low-temperature protection of permanent magnets.

[0018] Then, cryogenic liquid nitrogen is continuously supplied to the air gap cooling zone, the internal cooling passage of the casing, the parallel grid cooling passage, and the internal cooling passage of the conductor. Cryogenic liquid nitrogen is also introduced into the internal cooling passage of the slot insulation, the surface cooling passage of the permanent magnet, the surface cooling passage of the rotor core, and the internal cooling passage of the shaft until the overall temperature of the machine reaches the target deep cryogenic temperature.

[0019] A control system for a fully-range ultra-rapid cryogenic cooling shielded motor structure includes: a segmented temperature control module, a cryogenic sealed chamber, a cooling closed-loop recovery heat exchange component, and a multi-stage medium supply system; the segmented temperature control module is used to issue commands for switching cooling media and adjusting medium flow based on temperature sensing data from the stator cooling zone, rotor gap cooling zone, and air gap cooling zone; the cryogenic sealed chamber houses the fully-range ultra-rapid cryogenic cooling shielded motor structure and has a medium return collection chamber at the bottom for collecting cooling media from the stator cooling zone, rotor gap cooling zone, and air gap cooling zone. Low-temperature exhaust gas discharged from the rotor gap cooling zone, air gap cooling zone, and all cooling channels; a closed-loop cooling recovery heat exchange component is used to exchange heat with the low-temperature exhaust gas collected in the medium return collection chamber and then transmit it to the multi-stage medium supply system; the multi-stage medium supply system uses the exhaust gas after heat exchange to pre-cool low-temperature gaseous nitrogen and liquid nitrogen, and under the action of commands for switching cooling media and adjusting medium flow, low-temperature gaseous nitrogen and / or low-temperature liquid nitrogen are input to each zone through the main injection pipelines connected to the stator cooling zone, rotor gap cooling zone, and air gap cooling zone respectively.

[0020] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0021] 1. Multi-layer flow channel design throughout the entire area, resulting in high heat exchange efficiency and fast cooling speed: This invention features multi-layer independent cooling channels throughout the stator and rotor, allowing the cooling medium to directly reach core components such as windings, slot insulation, permanent magnets, and shafts. Compared to traditional external single cooling structures, the heat exchange area is significantly increased, enabling ultra-fast deep cooling from room temperature to -196℃, meeting the stringent requirements of rapid start-up and low-temperature impact testing.

[0022] 2. Multi-stage gradient medium cooling effectively resists low-temperature stress damage: The multi-stage cooling mode of pre-cooling with low-temperature gaseous nitrogen and deep cooling with liquid nitrogen is adopted. The overall temperature of the motor is first reduced gradually, and then liquid nitrogen is introduced to achieve extreme deep cooling. This completely avoids the ultra-large temperature difference stress generated by the motor directly contacting liquid nitrogen at room temperature, and prevents failures such as winding insulation brittleness, permanent magnet failure, and structural deformation, thereby improving the service life of the equipment.

[0023] 3. Integrated insulation and cooling, compact structure and easy assembly: The pre-formed groove insulation skeleton with built-in cooling channel is adopted to integrate the motor insulation components and cooling channels into one, eliminating the need for additional external wrapping pipes, simplifying the overall structure, reducing assembly difficulty, and ensuring stable insulation performance in deep low temperature environments.

[0024] 4. Three independent flow channels for rotor, flexible temperature control and uniform temperature field: The rotor is equipped with three independent flow channels: permanent magnet inter-sleeve channel, shaft side channel and hollow shaft channel. The medium in each channel can be adjusted individually, which can effectively improve the rotor temperature field distribution and avoid local overheating or undercooling for different areas of the rotor.

[0025] 5. Supports synchronous cooling under load, with strong realism in operating condition simulation: This invention can realize the motor running and cooling at the same time, perfectly replicating the actual service state of the liquid oxygen and liquid methane cryogenic medium pump "operation + deep cooling", and the test and operation data have higher reference value.

[0026] 6. Closed-loop cold energy recovery for energy saving and consumption reduction: A closed-loop cold energy recovery heat exchange component is set up to recover and utilize the residual cold energy of the low-temperature exhaust gas to pre-cool the new incoming medium, which greatly improves the cold energy utilization rate and reduces the long-term energy consumption of the entire equipment.

[0027] 7. Independent zone control, adaptable to multiple working conditions: The chamber zone jet and the medium parameters of each cooling channel are independently adjustable. Under deep cryogenic conditions, it can continuously supply liquid to the stator and rotor air gap and stator grid channel in a directional manner. It is specially adapted to the cryogenic medium pump compression operation conditions, and one machine can take into account both test and actual production operation.

[0028] 8. Dehumidification and anti-clogging design, high operational reliability: Low-temperature gaseous nitrogen has both pre-cooling and dehumidification functions, which can remove water vapor inside pipes and components in advance, avoid frost and flow channel blockage in deep low temperature environments, and ensure long-term continuous and stable operation of equipment. Attached Figure Description

[0029] Figure 1 This is a three-dimensional structural diagram of the shielded motor structure with full-domain ultra-fast deep cooling proposed in this invention.

[0030] Figure 2 This is an exploded view of the shaft side of the motor structure of the full-domain ultra-fast cryogenic cooling shielded motor proposed in this invention.

[0031] Figure 3 This is a front view of the shielded motor structure for full-domain ultra-fast cryogenic cooling proposed in this invention.

[0032] Figure 4 This is a schematic diagram of the stator core and end plate structure of the full-domain ultra-fast cryogenic cooling shielded motor structure proposed in this invention.

[0033] Figure 5 The images show cross-sectional views of the stator and rotor of the shielded motor structure with full-range ultra-fast cryogenic cooling proposed in this invention.

[0034] Figure 6 This is a front view of the stator end plate of the full-domain ultra-fast cryogenic cooling shielded motor structure proposed in this invention.

[0035] Figure 7This is a schematic diagram of the stator cooling medium flow in the full-domain ultra-fast cryogenic cooling shielded motor structure proposed in this invention.

[0036] Figure 8 This is a schematic diagram of the whole-domain ultra-fast deep cooling shielded motor structure with embedded cooling pipes in the winding coil and slot insulation opening structure proposed in this invention.

[0037] Figure 9(a) shows the cooling effect of the stator housing of a conventional shielded motor structure with cooling medium circulating through it; Figure 9(b) shows the cooling effect of the stator housing and air gap of the shielded motor structure with cooling medium circulating through them together; and Figure 9(c) shows the cooling effect of the shielded motor structure proposed in this invention with cooling medium circulating through it.

[0038] Figure 10 This is a block diagram of the cryogenic cooling system proposed in this invention.

[0039] The markings in the diagram are as follows: 1. Stator core; 1-1. Parallel grid-like cooling path; 1-2. Micro-through-hole cooling path; 2-1. First end plate; 2-2. Second end plate; 2-101. First cooling path; 2-102. Second cooling path; 3. Winding; 4. Stator shielding sleeve; 5. Rotor shielding sleeve; 6. Permanent magnet; 6-1. Surface cooling path of permanent magnet; 7. Rotor core; 7-1. Surface cooling path of rotor core; 8. Shaft; 8-1. Internal cooling path of shaft; 9. Housing; 9-1. Internal cooling path of housing; 10. Stator hot and cold counter-current flow path; 11. Slot insulation frame; 11-1. Internal cooling path of slot insulation; 12. Internal cooling path of conductor. Detailed Implementation

[0040] This embodiment provides a shielded motor structure for ultra-fast, full-range cryogenic cooling. For example... Figure 1 , Figure 2 , Figure 3 , Figure 10 As shown, the cryogenic sealed chamber adopts a sealed, pressure-resistant, and heat-insulating structure. The shielded motor inside is equipped with a stator shielding sleeve 4 and a rotor shielding sleeve 5, dividing the internal space of the chamber into three independent sealed chambers: a stator cooling zone, a rotor gap cooling zone, and an air gap cooling zone. The cooling control method is as follows: Figure 10As shown, each chamber is equipped with a zoned main injection pipeline. A closed-loop system, consisting of a multi-segment temperature control module, a cryogenic sealed chamber, a cold energy closed-loop recovery heat exchange component, and a multi-stage media supply system, enables independent media supply and pressure regulation for each chamber. The segmented temperature control module issues commands to switch cooling media and adjust media flow based on temperature sensor data from the stator cooling zone, rotor gap cooling zone, and air gap cooling zone. The cryogenic sealed chamber incorporates a full-range, high-speed, deep-cryogenic cooling shielded motor structure and has a media return collection chamber at the bottom. This chamber collects the cryogenic exhaust gas from the stator cooling zone, rotor gap cooling zone, air gap cooling zone, and all cooling channels. The closed-loop cooling recovery heat exchange component heats the cryogenic exhaust gas collected in the media return collection chamber. Transmitted to a multi-stage media supply system; the multi-stage zoned media supply system integrates two main pipelines: a cryogenic gaseous nitrogen pre-cooling branch and a liquid nitrogen cryogenic branch. The ends of the main pipelines are connected to multi-component flow valve groups. The exhaust gas after heat exchange is used to pre-cool the cryogenic gaseous nitrogen and liquid nitrogen. Under the action of switching cooling media and adjusting media flow commands, the main injection pipelines of each zone can independently complete the media switching, flow and pressure regulation of the built-in cooling channels of the stator cooling area, the cooling channels of the rotor gap cooling area, and the cooling channels of the motor stator and rotor air gap.

[0041] 1. Stator side channel assembly implementation

[0042] like Figure 2 As shown, the motor housing 9 has an internal cooling channel 9-1 machined inside, and the stator core 1 has multiple sets of parallel grid-shaped cooling channels 1-1 machined on its outer surface. The number of sets of parallel grid-shaped cooling channels is the same as the number of stator slots. Each set of parallel grid-shaped cooling channels is a grid structure composed of multiple parallel cooling channels.

[0043] like Figure 8 As shown, an integrated pre-formed slot insulation skeleton 11 is assembled inside the stator slot of the motor. This skeleton has both insulation and cooling functions, and an internal cooling channel 11-1 is opened through the slot insulation along the axial direction. On the wall surface of each tooth of the stator core 1 that contacts the stator slot insulation skeleton 11, densely drilled micro-through-hole cooling channels 1-2 are uniformly drilled. The micro-through-hole cooling channels 1-2 are used for local fine cooling of the stator only through low-temperature gaseous nitrogen introduced by the partitioned main injection pipe. The winding 3 is arranged close to the slot insulation skeleton 11. The coil adopts a prefabricated structure concentrated winding coil. A liquid nitrogen cooling pipe is pre-embedded inside each turn of the conductor as an internal cooling channel 12, forming an embedded cooling pipe in the coil, which is the core heat exchange component in the deep cooling stage.

[0044] like Figure 4 , Figure 6 , Figure 7As shown, a first end plate 2-1 and a second end plate 2-2 are respectively assembled at both ends of the stator. Each end plate has a first cooling passage 2-101 and a second cooling passage 2-102 machined at intervals. The positions of the first cooling passage 2-101 and the second cooling passage 2-102 correspond one-to-one with the stator slots and the slot insulation frame 11 installed within the slots. Specifically, the tiny through-hole cooling passage 1-2 on the periphery of one end of the internal cooling passage 11-1 of the slot insulation connects to the parallel grid-like cooling passage 1-1 on the outer surface of the stator core through the first cooling passage 2-101 on one end plate. The other end of the internal cooling passage 11-1 of the slot insulation connects to the second cooling passage 2-102 on the other end plate, forming a complete stator hot and cold opposing flow path 10. This allows for the reversible flow of the cooling medium between the two ends of the stator axially, resulting in more uniform stator cooling. The second cooling passage 2-102 is located on the first end plate 2-1 and the second end plate 2-2, and its position corresponds one-to-one with the stator slots and the slot insulation frame 11 installed within the slots. The second cooling passage 2-102 has a dual function: firstly, it serves as the lead-out channel for winding 3—after winding 3 is wound onto the stator teeth, its lead-out wires pass through the second cooling passage 2-102 to the outside of the end plate, facilitating connection to an external power source; secondly, it serves as the medium interface channel for the internal cooling passage 11-1 of the slot insulation—the slot insulation skeleton 11 is assembled inside the stator slot, with both ends extending axially and one end connected to the second cooling passage 2-102, exposing the opening of the internal cooling passage 11-1 of the slot insulation to the outside of the end plate, aligning with and communicating with the external cooling medium pipeline, thereby allowing low-temperature gaseous nitrogen or liquid nitrogen to directly enter the internal cooling passage 11-1 of the slot insulation for heat exchange via the pipeline interface on the outside of the end plate. Thus, the second cooling passage 2-102 simultaneously realizes both the winding lead-out function and the external connection of the internal cooling passage of the slot insulation.

[0045] The internal cooling passage 9-1 of the casing, the parallel grid-shaped cooling channel 1-1 on the outer surface of the stator core, the micro-through hole cooling passage 1-2 of the stator core teeth, the internal cooling passage 11-1 of the preformed groove insulation, and the internal cooling passage 12 of the conductor are independent of each other, but can also achieve zoned coordinated heat exchange through the cooperation of the end plates on both sides of the stator and the above-mentioned pipelines, together forming a whole-area built-in cooling channel group for the stator cooling zone.

[0046] 2. Rotor-side channel assembly implementation

[0047] like Figure 5 As shown, the motor rotor adopts a surface-mounted permanent magnet structure, with permanent magnets 6 attached to the outer circumference of the rotor core 7. The rotor shielding sleeve 5 is fixed to the outside of the permanent magnets 6, serving the dual function of protecting the permanent magnets and acting as a rotor shield. A first rotor cooling channel, namely the permanent magnet surface cooling channel 6-1, is formed between the shaping gap between adjacent permanent magnets 6 and the inner surface of the rotor shielding sleeve 5. This channel extends axially, allowing a medium to flow through it and directly remove heat from the permanent magnets and the rotor shielding sleeve.

[0048] The groove reserved on the outer circular surface of the rotor core 7 and the inner surface of the permanent magnet 6 form a second rotor cooling channel, namely the rotor core surface cooling channel 7-1. This channel is located between the permanent magnet and the rotor core and can effectively cool the back side of the permanent magnet and the rotor core.

[0049] like Figure 2 As shown, the motor shaft 8 adopts a hollow structure, and its internal cavity forms a third rotor cooling channel, namely the internal cooling channel 8-1. Figure 1 As shown, the three rotor cooling channels mentioned above—the permanent magnet surface cooling channel 6-1, the rotor core surface cooling channel 7-1, and the shaft internal cooling channel 8-1—are each independent, all running along the rotor axial direction, and connected to the multi-stage zoned media supply system via rotary joints or non-contact sealing structures. Figure 10 As shown, low-temperature gaseous nitrogen or liquid nitrogen can be introduced separately according to the real-time temperature requirements of each area of ​​the rotor to achieve gradient cooling and precise temperature control in the rotor gap cooling area.

[0050] 3. Air gap section channel assembly implementation

[0051] like Figure 5 As shown, the stator shielding sleeve 4 is fixed to the inner surface of the stator core, and the rotor shielding sleeve 5 is fixed to the outer surface of the rotor permanent magnet. The gap between the stator shielding sleeve 4 and the rotor shielding sleeve 5 is the air gap cooling zone. The air gap cooling zone is physically isolated from the stator cooling zone and the rotor cooling zone through the shielding sleeve, preventing cross-contamination of air. The multi-stage medium supply system has independent zoned injection pipelines leading into the air gap cooling zone, which can inject low-temperature gaseous nitrogen or liquid nitrogen into the annular gap to directly cool the stator shielding sleeve 4, the rotor shielding sleeve 5, and the air gap between them. The medium flow rate and pressure in this air gap cooling zone can be individually controlled by its corresponding flow regulating valve to meet the differentiated heat dissipation requirements of the air gap area during different stages of motor operation, including pre-cooling, deep cooling, and load operation.

[0052] 4. Implementation of Media Recovery and Temperature Control Component Assembly

[0053] Combination Figure 1 , Figure 2 , Figure 7 A medium reflux collection chamber is set at the bottom of the cryogenic sealed chamber. All cryogenic exhaust gases from the stator cooling zone, rotor gap cooling zone, air gap cooling zone, and all built-in cooling channels converge into this medium reflux collection chamber. All built-in cooling channels include: internal cooling channel 9-1 of the casing, parallel grid-like cooling channel 1-1 on the outer surface of the stator core, micro-through-hole cooling channel 1-2 for the stator core teeth, internal cooling channel 11-1 for the slot insulation, internal cooling channel 12 for the conductors, surface cooling channel 6-1 for the permanent magnets, surface cooling channel 7-1 for the rotor core, and internal cooling channel 8-1 for the shaft. Figure 10 As shown, the outlet of the medium reflux collection chamber is connected to a cold energy closed-loop recovery heat exchange component. The cold energy output end of the heat exchange component is then connected to the front end of the multi-stage medium supply system. The residual cold energy of the exhaust gas is used to pre-cool the newly introduced low-temperature gaseous nitrogen and liquid nitrogen, thereby realizing the closed-loop recovery and recycling of cold energy.

[0054] Temperature sensors are installed at key locations such as the motor housing 9, stator core 1, winding 3, slot insulation frame 11, surface-mount permanent magnet 6, rotor shielding sleeve 5, hollow shaft 8, air gap, and bearings. All sensors are electrically connected to the segmented temperature control module to form a closed-loop intelligent temperature control system, which dynamically regulates the medium type, flow rate, and pressure of each cooling zone and cooling channel.

[0055] 5. On-site operation and implementation

[0056] The assembled cooling channels are sequentially connected to the corresponding zone's main injection pipeline, multi-stage media supply system branch pipeline, and motor power line. A comprehensive inspection of the cryogenic sealed chamber, each cooling channel, and pipeline joints is conducted to ensure the overall airtightness and prevent leaks. This implementation process relies on a layered, differentiated built-in cooling channel hardware structure and a segmented temperature-controlled zoned nitrogen / liquid nitrogen mixing method to achieve phased, full-area gradient cooling. Each channel is matched with a dedicated media supply logic according to its structural function, balancing rapid cryogenic cooling with insulation and cryogenic protection requirements for permanent magnets. The process is divided into two operating conditions: shutdown pre-cooling and load-bearing operation cooling.

[0057] a. Shutdown Pre-cooling Mode: Keep the motor powered off, the segmented temperature control module initially determines the overall machine temperature to be normal, and issues a command to completely shut down the liquid nitrogen cryogenic branch, while only fully opening the low-temperature gaseous nitrogen pre-cooling branch. The low-temperature gaseous nitrogen is distributed to the cooling channels of each cooling zone through a multi-stage media supply system:

[0058] The stator-side dedicated nitrogen passage prioritizes gas supply: the micro-through-hole cooling passage 1-2 of the stator core teeth is a dedicated nitrogen passage, through which pure low-temperature gaseous nitrogen is continuously introduced at a small flow rate to purge the gap between the stator core and the slot insulation skeleton 11; at the same time, nitrogen is simultaneously introduced into the parallel grid-like cooling passage 1-1 on the outer surface of the stator core, the internal cooling passage 9-1 of the housing, and the internal cooling passage 11-1 of the pre-formed slot insulation, which, together with the stator end plate forming the stator hot and cold counteracting flow path 10, uniformly reduces the overall temperature of the stator; the internal cooling passage 12 of the conductor only circulates nitrogen at this time and does not send liquid medium to avoid instantaneous ultra-low temperature impact.

[0059] The rotor has three independent cooling channels that are simultaneously supplied with pure nitrogen: permanent magnet surface cooling channel 6-1, rotor core surface cooling channel 7-1, and shaft internal cooling channel 8-1. These three channels are parallel and provide full-area pre-cooling, which simultaneously reduces the initial temperature difference between the permanent magnet, rotor shielding sleeve, and shaft.

[0060] Nitrogen gas is simultaneously injected from the main injection pipelines of the three sections—stator cooling zone, rotor gap cooling zone, and air gap cooling zone—within the cryogenic sealed chamber to pre-cool the entire sealed environment and isolate it from ambient temperature heat sources.

[0061] The entire system uses pure nitrogen for continuous heat exchange and dehumidification, and the temperature of the whole unit drops evenly and stably to -80℃~-120℃. There are no liquid media in contact with the components throughout the process, which eliminates the huge temperature difference stress between room temperature and liquid nitrogen at 200℃ from the source, and avoids problems such as insulation brittleness, permanent magnet demagnetization, and pipeline frost and blockage.

[0062] When the temperature sensor indicates that the entire unit has reached the pre-cooling threshold that meets the requirements for low-temperature protection of insulation and permanent magnets, the segmented temperature control module automatically closes the nitrogen branch valves and gradually opens the liquid nitrogen cryogenic branch, entering the gas nitrogen + liquid nitrogen partitioned mixed transition cooling stage. Based on the structural attributes of each channel, the medium ratio is adjusted accordingly: the cooling passage 12 inside the conductor, the parallel grid-like cooling passage 1-1 on the outer surface of the stator core, and the cooling passage 9-1 inside the casing are liquid nitrogen priority heat exchange channels, which greatly increases the liquid nitrogen supply ratio and relies on the high latent heat of vaporization of liquid nitrogen to quickly lower the high temperature of the winding core; the cooling passage 11-1 inside the preformed slot insulation and the three cooling channels of the rotor adopt a high nitrogen and low liquid nitrogen mixed ratio to slow down the cooling rate and protect the insulation and permanent magnets; the micro-through-hole cooling passage 1-2 in the stator core teeth is always only supplied with pure nitrogen and continuously purged to prevent liquid accumulation and freezing in the gaps; at the same time, liquid nitrogen is continuously and directionally supplied to the air gap between the stator and rotor to enhance the air gap heat exchange. The system collects real-time temperature monitoring data for each area of ​​the rotor. The rotor's three channels can be individually switched between pure nitrogen or a nitrogen-liquid mixture to dynamically balance the rotor temperature field until the entire machine stably reaches the target deep cryogenic temperature of -196℃.

[0063] b. Load-bearing operation cooling mode: The low-temperature gaseous nitrogen pre-cooling branch is activated to supply gas to the entire machine, performing basic and gradual pre-cooling; after the segmented temperature control module monitors the temperature of the entire machine and it drops to -50℃, which is below the load-bearing operation pre-cooling threshold, it automatically issues a closing command to connect the motor power supply, and the motor starts to run under load; in the initial stage of operation, pure nitrogen is continuously supplied to the entire machine to complete gradient cooling; after the temperature reaches the pre-cooling range of -80℃ to -120℃, the system automatically switches to the gaseous nitrogen + liquid nitrogen mixed gradient cooling mode.

[0064] During operation, the segmented temperature control module collects the temperature rise data of the winding and permanent magnet in real time, and dynamically adjusts the liquid nitrogen ratio of the internal cooling path 12 of the conductor and the parallel grid-shaped cooling path 1-1 on the outer surface of the stator core to match the heat generated during operation; the motor keeps energized throughout the process and the layered flow channel synchronously gradients the cooling, achieving deep cooling while operating.

[0065] If the motor and pump head perform compression operations for a long time, the system switches to steady-state constant temperature control logic: continuously supplying liquid nitrogen at a high flow rate to the stator-rotor air gap, the internal cooling passage 9-1 of the housing, the parallel grid-like cooling passage 1-1 on the outer surface of the stator core, and the internal cooling passage 12 of the conductor as the main cold source; maintaining a low liquid nitrogen + auxiliary nitrogen mixture supply in the internal cooling passage 11-1 of the slot insulation and the three channels of the rotor; and continuously purging and dehumidifying with a small amount of nitrogen in the micro-through-hole cooling passage 1-2 of the stator core, so as to maintain the overall machine in a stable low temperature steady-state operation at -196℃ for a long time.

[0066] Throughout the operation, the segmented temperature control module, in conjunction with the global temperature sensor, the independent flow control valves of each channel, and the compartment zone control valves, automatically adjusts the medium type, flow rate, and pressure of each chamber and each cooling channel based on the real-time temperature difference at each measuring point. The layered channel + zone ratio control coupling design achieves uniform temperature field across the entire machine. All low-temperature nitrogen / liquid nitrogen mixture exhaust gases discharged from all chambers and cooling channels are uniformly collected into the medium return collection chamber and sent to the cold energy closed-loop recovery heat exchange component. The residual cold energy of the exhaust gas is used to pre-cool the newly introduced low-temperature gaseous nitrogen and liquid nitrogen, smoothing the temperature difference of the medium inlet path, and simultaneously realizing the recycling of cold energy and energy saving.

[0067] After the test or continuous operation is completed, first shut down the liquid nitrogen cryogenic branch, and then gradually shut down the low-temperature gaseous nitrogen precooling branch; after the motor naturally returns to a safe temperature, cut off the motor power supply, open the cryogenic sealed chamber, and complete the single operation process.

[0068] As shown in Figures 9(a), 9(b), and 9(c), when the ambient temperature is 20°C, the conventional shielded motor structure with cooling medium circulating through the stator housing only reduces the temperature of various parts of the motor to between -80°C and -65°C after 7000s; the shielded motor structure with cooling medium circulating through both the stator housing and the air gap only reduces the motor bearing temperature to -45°C after 1750s, and the temperature of other parts of the motor only reduces to between -80°C and -75°C; while the shielded motor structure with cooling medium circulating through it proposed in this invention only requires 200s to reduce the temperature of various parts of the motor to -80°C, and the motor bearing temperature also reduces to -70°C after 700s. When the ambient temperature is -80℃, the conventional shielded motor structure with cooling medium circulating through the stator housing only reduces the temperature of various parts of the motor to between -196℃ and -175℃ after 7000 seconds. The shielded motor structure with cooling medium circulating through both the stator housing and air gap reduces the motor bearing temperature to -160℃ after 1750 seconds, and the temperature of other parts of the motor only reduces to between -196℃ and -190℃. However, the shielded motor structure proposed in this invention, with its cooling medium circulating through the stator housing, can reduce the temperature of various parts of the motor to -196℃ in just 200 seconds, and the motor bearing temperature to -180℃ after 700 seconds. Compared with the two existing cooling methods, the structure of this invention can rapidly and uniformly reduce the temperature of various parts of the motor to the target temperature range within 200 seconds, significantly improving both the cooling rate and temperature uniformity.

[0069] In summary, this invention features multiple independent built-in cooling channels throughout the stator and rotor of the motor. It employs a two-stage medium cooling process of gradient pre-cooling with low-temperature gaseous nitrogen and deep cooling with liquid nitrogen. Combined with compartment-zoned jet cooling, closed-loop cold energy recovery, and intelligent zoned temperature control design, it supports two working modes: motor shutdown pre-cooling and cooling under load. It can quickly and stably reduce the motor temperature from room temperature to a deep cryogenic temperature of -196℃, effectively avoiding structural and insulation damage caused by large temperature differences. It is also suitable for long-term deep cryogenic operation of liquid oxygen and liquid methane cryogenic medium pumps. The structure is compact, easy to assemble, and has a high cold energy utilization rate.

[0070] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included in the scope of protection set forth in the claims.

Claims

1. A shielded motor structure for ultra-fast cryogenic cooling across the entire domain, characterized in that, include: The machine includes a housing, a stator, and a rotor mounted on a rotating shaft. The rotor is covered with a rotor shielding sleeve, and the stator is covered with a stator shielding sleeve. The stator shielding sleeve is mounted on the outside of the rotor shielding sleeve. The cooling channels on the stator and the cooling channels inside the housing form a fully integrated cooling channel for the stator cooling area. The cooling channels on the rotor and the cooling passages inside the rotating shaft form a cooling channel for the rotor gap cooling area. The gap between the stator shielding sleeve and the rotor shielding sleeve forms an air gap cooling area channel. The method for rapid cryogenic cooling of the entire shielded motor structure is as follows: First, the stator cooling area, rotor gap cooling area, and air gap cooling area are pre-cooled with low-temperature gaseous nitrogen until the overall temperature reaches the pre-cooling threshold that meets the requirements for insulation and low-temperature protection of permanent magnets. Then, according to the principle of prioritizing the reduction of stator temperature, the stator cooling area, rotor gap cooling area, and air gap cooling area are gradually cryogenically cooled with liquid nitrogen until the overall temperature reaches the target deep low temperature.

2. The full-range ultra-fast cryogenic cooling shielded motor structure according to claim 1, characterized in that, The cooling channels on the stator include: n sets of parallel grid-shaped cooling channels, micro-through-hole cooling channels, internal cooling channels of slot insulation, and internal cooling channels of conductors; the n sets of parallel grid-shaped cooling channels are opened on the outer surface of the stator core, where n is the number of stator slots; the micro-through-hole cooling channels are drilled on the wall surface where the stator core teeth contact the stator slot insulation skeleton; the internal cooling channels of slot insulation are cooling channels that run through the axial direction of the stator slot insulation skeleton; and the internal cooling channels of conductors are liquid nitrogen cooling pipes pre-embedded in the winding coils wound on the stator core.

3. The full-range ultra-fast cryogenic cooling shielded motor structure according to claim 2, characterized in that, The stator end plates on both sides are respectively machined with a first cooling passage and a second cooling passage. The first cooling passage and the second cooling passage machined on the stator end plates, together with the internal cooling passage of the slot insulation and the micro-through hole cooling passage, form a stator hot and cold counterflow path.

4. The full-range ultra-fast cryogenic cooling shielded motor structure according to claim 3, characterized in that, The positions of the first cooling passage and the second cooling passage correspond one-to-one with the stator slot and the slot insulation frame installed in the slot. The small through-hole cooling passage on the periphery of one end of the internal cooling passage of the slot insulation is connected to the parallel grid-shaped cooling passage through the first cooling passage on one side of the stator end plate. The other end of the internal cooling passage of the slot insulation is connected to the second cooling passage on the other side of the stator end plate.

5. The full-range ultra-fast cryogenic cooling shielded motor structure according to claim 4, characterized in that, The cooling channels opened on the rotor include: a permanent magnet surface cooling channel formed between the shaping gap between adjacent permanent magnets and the inner surface of the rotor shield sleeve, and a rotor core surface cooling channel formed between the groove reserved on the outer circular surface of the rotor core and the inner surface of the permanent magnet.

6. The full-range high-speed deep cryogenic cooling shielded motor structure according to claim 5, characterized in that, When the shielded motor structure operates in the shutdown pre-cooling mode: First, keep the motor powered off and continuously introduce low-temperature gaseous nitrogen into the micro-through-hole cooling channel, the parallel grid cooling channel, the internal cooling channel of the housing, the internal cooling channel of the slot insulation, and the internal cooling channel of the conductor, and introduce low-temperature gaseous nitrogen into the cooling channel of the permanent magnet surface, the cooling channel of the rotor core surface, and the internal cooling channel of the shaft until the temperature of the whole machine reaches the pre-cooling threshold that meets the requirements of insulation and low-temperature protection of permanent magnets. Then, cryogenic liquid nitrogen is introduced into the cooling channels inside the conductors, the parallel grid cooling channels, and the cooling channels inside the casing. Cryogenic liquid nitrogen is also introduced into the cooling channels inside the slot insulation, the cooling channels on the surface of the permanent magnets, the cooling channels on the surface of the rotor core, and the cooling channels inside the shaft. Cryogenic liquid nitrogen is introduced into the air gap cooling zone until the overall temperature of the machine reaches the target deep cryogenic temperature.

7. The full-range high-speed deep cryogenic cooling shielded motor structure according to claim 5, characterized in that, When the shielded motor structure operates in the load-cooled mode: First, low-temperature gaseous nitrogen is introduced into the stator cooling zone, rotor gap cooling zone, and air gap cooling zone until the overall machine temperature reaches the pre-cooling threshold for load operation. Then, the motor is instructed to run under load, and low-temperature gaseous nitrogen is introduced into the stator cooling zone, rotor gap cooling zone, and air gap cooling zone until the overall machine temperature reaches the pre-cooling threshold that meets the requirements for insulation and low-temperature protection of permanent magnets. Then, cryogenic liquid nitrogen is continuously supplied to the air gap cooling zone, the internal cooling passage of the casing, the parallel grid cooling passage, and the internal cooling passage of the conductor. Cryogenic liquid nitrogen is also introduced into the internal cooling passage of the slot insulation, the surface cooling passage of the permanent magnet, the surface cooling passage of the rotor core, and the internal cooling passage of the shaft until the overall temperature of the machine reaches the target deep cryogenic temperature.

8. A control system for the full-range ultra-fast cryogenic cooling shielded motor structure as described in claim 1, characterized in that, include: The segmented temperature control module is used to issue commands for switching cooling media and adjusting media flow based on temperature sensing data from the stator cooling zone, rotor gap cooling zone, and air gap cooling zone. The low-temperature sealed chamber is equipped with the full-range ultra-fast deep cooling shielded motor structure and a medium reflux collection chamber at the bottom. The medium reflux collection chamber is used to collect the low-temperature exhaust gas discharged from the stator cooling zone, rotor gap cooling zone, air gap cooling zone and all cooling channels. A closed-loop cooling recovery heat exchange component is used to exchange heat with the low-temperature exhaust gas collected in the medium reflux collection chamber and then transmit it to a multi-stage medium supply system. and, The multi-stage medium supply system uses the exhaust gas after heat exchange to pre-cool the low-temperature gaseous nitrogen and liquid nitrogen. Under the action of the command to switch the cooling medium and adjust the medium flow rate, the system supplies low-temperature gaseous nitrogen and / or low-temperature liquid nitrogen to each zone through the main injection pipeline that is connected to the stator cooling zone, rotor gap cooling zone and air gap cooling zone respectively.

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