Ventilation cooling structure with sub-cooler and ventilation cooling method

Abstract

The application provides a ventilation cooling structure with a sub-cooler and a ventilation cooling method, and belongs to the technical field of large motor cooling. The application solves the problems of low cooling efficiency, uneven temperature distribution, poor adaptability and poor cooling effect of the stator end portion in the prior art. The ventilation cooling structure comprises a top cover, a main cooler assembly, a sub-cooler assembly, a large end cover, an inner end cover and an axial flow fan. The sub-cooler assembly is installed in the top cover to form a sub-cooling air path. A stator assembly is installed in a cavity formed by the top cover and the inner end cover. A stator core of the stator assembly is divided into a plurality of alternating air inlet areas and air outlet areas along the axial direction. A rotor assembly is connected with the stator assembly. The main cooler assembly is arranged below the cavity of the stator assembly. Cooling air flows out of the main cooler assembly, enters a cavity surrounded by the large end cover and the inner end cover through an air duct, and is divided into three paths after being pressurized by the axial flow fan at the air outlet of the cavity and then enters the motor. The application is mainly used for motor cooling.

Description

Technical Field

[0001] This invention belongs to the field of large motor cooling technology, and in particular relates to a ventilation cooling structure and ventilation cooling method with an auxiliary cooler. Background Technology

[0002] During operation, large generators generate significant heat in their stator, rotor windings, and core due to electromagnetic and mechanical losses. If this heat cannot be dissipated promptly, it accelerates insulation aging, causes component deformation, and can even lead to malfunctions. The ventilation and cooling structure is the core system ensuring safe, efficient, and long-term operation. Its core design principles are "uniform air distribution, efficient heat exchange, capacity adaptation, and redundancy." The core function of the ventilation system is to create a circulation channel for the cooling medium, ensuring that the medium flows evenly through the heat-generating components and removes heat. It mainly consists of the airflow structure, air supply components, and guide components. While the airflow design varies slightly between different generator types, the core logic remains the same. Large generator airflow systems all employ a "closed-loop" design to prevent external dust and moisture from entering, protecting the insulation. Clear airflow zones are defined along the axial and radial directions to achieve orderly airflow circulation. Specifically, it includes: Radial airflow: Primarily used for cooling the stator core and stator windings, the stator core is divided into multiple annular small air chambers along the axial direction by the frame partition, alternating as air inlet and outlet zones. Cold air enters from the back of the core, passes radially through the core ventilation slots and stator bar gaps, absorbs heat, and is discharged from the outlet zone, forming a radial airflow circulation to ensure uniform temperature of the core and windings. Axial airflow: mainly used for cooling the rotor windings and end structures. Axial fans are installed at both ends of the rotor to drive the cooling medium to flow axially. At the same time, the straight section of the rotor winding is divided into multiple sections along the axial direction, corresponding to the number of stator air zones, with cold air zones and hot air zones arranged alternately. End airflow: designed for the stator and rotor ends, the end windings adopt an arc arrangement with reserved ventilation channels in the gaps, and guide plates are installed to avoid airflow dead zones, ensuring sufficient cooling of end windings, retaining rings, and other components, and preventing local overheating.

[0003] However, a single ventilation structure has low heat exchange efficiency and cannot properly distribute airflow to fully cool all heat-generating components, resulting in overheating of the unit; the gas in the stator inlet area will have a large temperature rise of about 15K after passing through the fan and the stator bar ends, resulting in a high inlet temperature and failing to cool the stator section well; relying solely on the main cooler to cool the gas will result in a small heat margin and uncertain airflow distribution. Summary of the Invention

[0004] In view of this, the present invention aims to propose a ventilation cooling structure and ventilation cooling method with an auxiliary cooler to solve the problems of low cooling efficiency, uneven temperature distribution, poor adaptability, and poor cooling effect of stator ends in large motors in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a ventilation and cooling structure with a secondary cooler, comprising a top cover, a main cooler assembly, a secondary cooler assembly, a stator assembly, a rotor assembly, a large end cover, an inner end cover, and an axial flow fan. The secondary cooler assembly is installed inside the top cover to form a secondary cooling air path. The stator assembly is installed below the top cover and in the cavity formed by the inner end cover. The stator core of the stator assembly is divided into several alternately arranged air inlet and outlet zones along the axial direction. The rotor assembly is connected to the stator assembly. The main cooler assembly is installed below the cavity of the stator assembly. The cooling air flows out of the main cooler assembly, enters the cavity formed by the large end cover and the inner end cover through the air duct, and is pressurized by the axial flow fan at the air outlet of the cavity before being divided into three paths to enter the motor.

[0006] Furthermore, the tube bundle, water chamber, and end cap of the auxiliary cooler are installed inside the top cover.

[0007] Furthermore, the tube bundle of the auxiliary cooler assembly is connected to the housing of the auxiliary cooler assembly, and the water chamber and end cover are installed to the housing through sealing gaskets and sealant and fixed with bolts.

[0008] Furthermore, the axial fan is a compressed axial fan, and the pressurized cooling air enters the rotor assembly first.

[0009] Furthermore, the auxiliary slots of the rotor assembly are arranged axially along the rotor body.

[0010] Furthermore, the second path of the pressurized cooling air from the axial fan flows into the motor air gap along the motor axial direction.

[0011] Furthermore, the third path of the cooling air pressurized by the axial fan first cools the stator end structure of the stator assembly, then enters the auxiliary cooler assembly for secondary cooling, and is then sent from the exhaust port of the auxiliary cooler assembly into the upper air inlet area of ​​the stator core, radially passing through the stator core ventilation slot and the stator bar gap.

[0012] Furthermore, the stator core of the stator assembly has an air collection cavity in the back air outlet area.

[0013] Furthermore, the auxiliary cooler is equipped with water flow rate and wind resistance adjustment mechanisms to balance the airflow in each air zone and control the stable operating temperature of the motor.

[0014] A ventilation cooling method with a ventilation cooling structure including a secondary cooler includes the following steps: Step 1: Cooling air flows out of the exhaust vent of the self-cooling unit and enters the cavity formed by the large end cover and the inner end cover; Step 2: The cooling air is pressurized by the axial fan and divided into three paths. The first path enters the rotor assembly and cools the rotor coil body and end coils through the auxiliary slot ventilation structure. The second path flows axially into the air gap to carry away the frictional heat between the stator assembly and the rotor assembly. The third path cools the stator end structure of the stator assembly. Step 3: The third cooling air enters the stator core air inlet area after being cooled twice by the auxiliary cooler, radially cooling the stator core and bars, and together with the gas from the first and second cooling air inlets, radially cooling the stator air outlet area. Step 4: The hot air after absorbing heat converges in the air outlet area on the back of the stator core and enters the main cooler assembly for heat dissipation, completing one closed-loop cycle.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention adds an auxiliary cooler assembly inside the top cover to perform secondary cooling on the high-temperature gas after passing through the stator end structure. This significantly reduces the gas temperature entering the stator core air intake area, thereby significantly improving the subsequent cooling capacity of the stator core and bars, and effectively reducing the average and maximum temperatures of the stator windings.

[0016] 2. The axial flow fan of this invention precisely divides the cooling air into three paths. The first path penetrates deep into the rotor and effectively cools the rotor coil body and ends using the secondary slot structure, solving the problem of difficult heat dissipation inside the rotor. The second path directly cools the air gap, carrying away the frictional heat between the stator and rotor, reducing interference with the cooling air in other areas. The third path specifically cools the stator end structure components that generate a large and concentrated amount of heat, thereby making the cooling of each heat-generating component inside the motor more balanced.

[0017] 3. The stator core of this invention adopts an axial segmented structure with alternating air inlet and outlet zones. Combined with the low-temperature cold air provided by the auxiliary cooler, the temperature distribution of the stator core along the axial direction is more uniform, greatly reducing the axial temperature difference. This effectively reduces the mechanical thermal stress caused by uneven thermal expansion and improves the stability and safety of motor operation.

[0018] 4. Due to the improved cooling effect, the motor can operate at a higher safe temperature, or allow a larger current load at the same temperature, thereby directly increasing the unit's output limit. At the same time, efficient cooling reduces ventilation losses, contributing to improved overall motor operating efficiency. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of a ventilation cooling structure with an auxiliary cooler according to the present invention; Figure 2 This is a front view of the auxiliary cooler assembly according to the present invention; Figure 3 A top view of the auxiliary cooler assembly according to the present invention; Figure 4 A side view of the auxiliary cooler assembly according to the present invention; Figure 5 This is a schematic diagram of the main airflow path of the present invention.

[0020] In the picture: 1-Top cover, 2-Main cooler assembly, 3-Secondary cooler assembly, 4-Stator assembly, 5-Rotor assembly, 6-Large end cover, 7-Inner end cover, 8-Axial fan. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0022] Detailed Implementation Method 1: See Figure 1-5 This embodiment describes a ventilation and cooling structure with a secondary cooler, including a top cover 1, a main cooler assembly 2, a secondary cooler assembly 3, a stator assembly 4, a rotor assembly 5, a large end cover 6, an inner end cover 7, and an axial flow fan 8. The secondary cooler assembly 3 is installed in the internal cavity of the top cover 1, forming a secondary cooling air path together with the top cover 1. The stator assembly 4 is fixed to the base and located below the top cover 1 within the cavity formed by the inner end cover 7. The stator core of the stator assembly 4 is designed axially with several alternately arranged air inlet and outlet zones. The air inlet zones have no... A baffle is provided to allow cold air to enter smoothly, and a baffle is provided in the air outlet area to guide hot air to flow out radially. The rotor assembly 5 is rotatably connected to the stator assembly 4 through bearings. The main cooler assembly 2 is located below the cavity where the stator assembly 4 is located. The cooling air flows out of the air outlet of the main cooler assembly 2, passes through a specific air duct and enters the sealed cavity formed by the large end cover 6 and the inner end cover 7. An axial flow fan 8 is installed at the air outlet of this cavity. After being pressurized by the fan, the cooling air is forced to be divided into three paths and precisely delivered to each cooling area inside the motor, realizing the diversion and cascade utilization of the cooling air.

[0023] Furthermore, the tube bundle, water chamber, and end cover of the auxiliary cooler assembly 3 are installed inside the top cover 1, so that the auxiliary cooler assembly 3 is completely embedded in the original outline of the motor, without needing to increase the lateral footprint of the motor. The structure is compact, and the top cover 1 itself acts as the outer shell of the auxiliary cooler assembly 3, reducing the number of parts and lowering the manufacturing cost.

[0024] Furthermore, to ensure that the auxiliary cooler does not leak cooling medium during long-term operation, the tube bundle of the auxiliary cooler assembly 3 is connected to the shell by expansion or welding. The water chamber and end cover are installed to the shell by a double sealing measure of sealing gasket and sealant. When tightening, the connecting bolts should be tightened evenly in stages according to the set torque, and anti-loosening marks should be made after tightening. This ensures that the auxiliary cooler can maintain good sealing performance under motor vibration environment and prevent water droplets from dripping into the motor and causing insulation accidents.

[0025] Furthermore, the axial fan 8 is a compressed axial fan. This type of fan can increase the gas pressure and overcome the airflow resistance. The pressurized cooling air mainly enters the rotor assembly 5 in the first path. Due to the high speed of the rotor, the centrifugal force in its internal space is large. The compressed fan can provide sufficient pressure head to force the cooling air to overcome the centrifugal force and enter the complex airflow channel inside the rotor, effectively cooling the rotor coil and iron core.

[0026] Furthermore, in order to achieve efficient cooling of the rotor coil body, the rotor assembly 5 is designed with a secondary slot. The secondary slot is arranged along the axial direction of the rotor body. After the first cooling air enters the rotor, part of it flows axially through the secondary slot and then radially enters the radial ventilation channel of the rotor body. This increases the ventilation area inside the rotor, changes the airflow path, and allows the cooling air to contact the heat-generating parts of the rotor coil more directly, greatly improving the heat exchange efficiency inside the rotor.

[0027] Furthermore, the second path of cooling air, pressurized by the axial fan 8, flows axially into the motor air gap. This path of air is mainly responsible for carrying away the heat generated by the shear friction between the inner surface of the stator and the outer surface of the rotor. Through the axial flow of the air gap, this path of air also plays an isolation role, reducing thermal interference between the first and third paths and ensuring the independence of their respective cooling areas.

[0028] Furthermore, the third path of cooling air pressurized by the axial fan 8 first flows downward or radially to cool the stator end structural components of the stator assembly 4, such as pressure rings, pressure fingers, and copper shields. These components generate a large amount of heat and are concentrated. After absorbing heat and heating up, this path of air then flows upward and enters the auxiliary cooler assembly 3 for secondary cooling. The low-temperature gas cooled by the auxiliary cooler assembly 3 is precisely sent from the outlet of the auxiliary cooler assembly 3 into the air inlet area at the upper end of the stator core. Since the gas temperature has already decreased, it can efficiently pass radially through the ventilation slots of the stator core and the gaps between the stator bars, providing powerful cooling to the stator core and bars, thus realizing the cascade management and reuse of heat.

[0029] Furthermore, in order to optimize the hydrodynamic characteristics of the air outlet side, an air collection cavity is set on the back of the stator core of stator assembly 4, that is, the air outlet area on the side away from the air gap. Hot air from each ventilation slot of the stator core gathers in the air collection cavity to form a stable flow field, and then circulates to the lower air inlet of the main cooler assembly 2. This reduces the eddy loss of airflow in the air outlet area, lowers the wind resistance, and improves the ventilation efficiency.

[0030] Furthermore, to adapt to the unit's operational needs under different seasons and loads, the auxiliary cooler assembly 3 is equipped with an adjustment device, allowing for the adjustment of its water flow rate and air resistance. For example, the cooling water flow rate can be adjusted via an electric valve, or the air resistance can be adjusted via guide vanes. During summer or high-load operation, the water flow rate is increased to enhance cooling; during winter or low-load operation, the water flow rate is reduced to save energy and prevent condensation. This adjustability effectively balances the airflow in each air zone, precisely controls the temperature of various parts of the motor within the optimal range, and improves the unit's operational flexibility and safety redundancy.

[0031] Furthermore, the ventilation and cooling method employing this ventilation and cooling structure includes the following steps: Step 1: Cooling air flows out of the outlet of the self-cooling unit 2 and enters the cavity formed by the large end cover 6 and the inner end cover 7; Step 2: The cooling air is pressurized by the axial fan 8 and divided into three paths. The first path enters the rotor assembly 5 and cools the rotor coil body and end coils through the auxiliary slot ventilation structure. The second path flows axially into the air gap to carry away the frictional heat between the stator assembly 4 and the rotor assembly 5. The third path cools the stator end structure of the stator assembly 4. Step 3: The third cooling air enters the stator core air inlet area after being cooled twice by the auxiliary cooler assembly 3, radially cooling the stator core and bars, and together with the gas from the first and second cooling air inlets, radially cooling the stator air outlet area. Step 4: The hot air after absorbing heat converges in the air outlet area on the back of the stator core and enters the main cooler assembly 2 for heat dissipation, completing one closed cycle.

[0032] The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A ventilation cooling structure with an auxiliary cooler, characterized in that: The system includes a top cover (1), a main cooler assembly (2), a secondary cooler assembly (3), a stator assembly (4), a rotor assembly (5), a large end cover (6), an inner end cover (7), and an axial fan (8). The secondary cooler assembly (3) is installed inside the top cover (1) to form a secondary cooling air path. The stator assembly (4) is installed below the top cover (1) and in the cavity formed by the inner end cover (7). The stator core of the stator assembly (4) is divided into several alternating air inlet and outlet areas along the axial direction. The rotor assembly (5) is connected to the stator assembly (4). The main cooler assembly (2) is located below the cavity of the stator assembly (4). The cooling air flows out from the main cooler assembly (2), enters the cavity formed by the large end cover (6) and the inner end cover (7) through the air duct, and is pressurized by the axial fan (8) at the air outlet of the cavity and then divided into three paths to enter the motor.

2. The ventilation cooling structure with an auxiliary cooler according to claim 1, characterized in that: The tube bundle, water chamber and end cap of the auxiliary cooler assembly (3) are installed inside the top cover (1).

3. The ventilation cooling structure with an auxiliary cooler according to claim 2, characterized in that: The tube bundle of the auxiliary cooler assembly (3) is connected to the shell of the auxiliary cooler assembly (3). The water chamber and the end cover are installed to the shell through sealing gaskets and sealant and fixed with bolts.

4. The ventilation cooling structure with an auxiliary cooler according to claim 1, characterized in that: The axial fan (8) is a compressed axial fan, and the pressurized cooling air enters the rotor assembly (5) in the first path.

5. A ventilation cooling structure with an auxiliary cooler according to claim 4, characterized in that: The auxiliary slots of the rotor assembly (5) are arranged along the axial direction of the rotor body.

6. A ventilation cooling structure with an auxiliary cooler according to claim 1, characterized in that: The second path of the pressurized cooling air from the axial fan (8) flows into the motor air gap axially.

7. A ventilation cooling structure with an auxiliary cooler according to claim 1, characterized in that: The cooling air from the pressurized axial fan (8) first cools the stator end structure of the stator assembly (4), then enters the auxiliary cooler assembly (3) for secondary cooling, and is then sent to the upper air inlet area of ​​the stator core through the air outlet of the auxiliary cooler assembly (3), and radially passes through the stator core ventilation slot and stator bar gap.

8. A ventilation cooling structure with an auxiliary cooler according to claim 1, characterized in that: The stator assembly (4) has an air collection cavity in the back air outlet area of ​​the stator core.

9. A ventilation cooling structure with an auxiliary cooler according to claim 1, characterized in that: The auxiliary cooler assembly (3) adjusts the water flow and wind resistance to balance the air volume of each air zone and control the stable operating temperature of the motor.

10. A ventilation cooling method with a ventilation cooling structure having a secondary cooler as described in any one of claims 1-9, characterized in that: It includes the following steps: Step 1: Cooling air flows out of the outlet of the self-cooling unit (2) and enters the cavity formed by the large end cover (6) and the inner end cover (7); Step 2: The cooling air is pressurized by the axial fan (8) and divided into three paths. The first path enters the rotor assembly (5) and cools the rotor coil body and end coil through the auxiliary slot ventilation structure. The second path flows axially into the air gap to carry away the frictional heat between the stator assembly (4) and the rotor assembly (5). The third path cools the stator end structure of the stator assembly (4). Step 3: The third cooling air enters the stator core air inlet area after being cooled twice by the auxiliary cooler assembly (3), radially cooling the stator core and bars, and together with the gas after the first and second air inlets merge, radially cooling the stator air outlet area. Step 4: The hot air after absorbing heat converges in the air outlet area on the back of the stator core and enters the main cooler assembly (2) for heat dissipation, completing one closed cycle.

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