Flywheel energy storage system and cooling method therefor

Abstract

The present application relates to the technical field of flywheel energy storage. Disclosed are a flywheel energy storage system and a cooling method therefor. The flywheel energy storage system comprises a rotor assembly and a housing, wherein the rotor assembly comprises a rotating shaft and a rotor, the rotor being coaxially mounted on the rotating shaft; an upper end of the rotating shaft passes through the housing and is sealingly and rotationally connected to the housing, and a lower end of the rotating shaft is rotationally connected to the housing; the rotor is disposed in the housing, and an upper water collection ring and a lower water collection ring are provided on upper and lower side edges of the rotor, respectively; a plurality of water cooling pipes are uniformly provided on an outer wall surface of the rotor in the circumferential direction of the rotor, upper ends of the water cooling pipes are in communication with the upper water collection ring, and lower ends of the water cooling pipes are in communication with the lower water collection ring; and a first water channel and a second water channel are provided inside the rotating shaft, a lower end of the first water channel extends below the rotor and is in communication with the lower water collection ring through a first water collection pipe, and a lower end of the second water channel extends above the rotor and is in communication with the upper water collection ring via a second water collection pipe. The present application provides a cooling structure, enabling a flywheel to effectively carry the heat out of a flywheel chamber.

Description

A flywheel energy storage system and its cooling method

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. 202510227090.6, filed on February 27, 2025, entitled "A Flywheel Energy Storage System and Cooling Method Thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of flywheel energy storage technology, specifically relating to a flywheel energy storage system and its cooling method. Background Technology

[0004] Flywheel energy storage systems are an advanced physical energy storage technology that uses an electric motor to drive a flywheel at high speed to store energy, and releases energy by using the flywheel to drive a generator when needed. The working principle of flywheel energy storage systems is based on the law of conservation of energy and the kinetic energy theorem, and achieves the mutual conversion and storage of electrical energy and mechanical energy through a bidirectional electric / generator reversible motor.

[0005] Significant breakthroughs have been achieved in flywheel energy storage technology, particularly in bidirectional motors that reverse between electric and generator operation, high-speed rotating body design, and control systems. Flywheel energy storage systems are suitable for power systems, used for power stabilization and peak shaving. In the power industry, to improve the electrical conversion efficiency of flywheel energy storage, the rotor and motor share a single chamber, which is kept in a vacuum state. This vacuum reduces frictional heat generation between the rotor and air, thus lowering flywheel efficiency. While this improves the efficiency of the flywheel energy storage system, the heat generated by the motor coils and the rotor during rotation cannot be effectively controlled. This results in prolonged operation where heat cannot dissipate from the chamber, leading to high surface temperatures on the flywheel casing and severely impacting safe operation. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this application is to propose a flywheel energy storage system and its cooling method. This application includes a cooling structure that enables the flywheel to effectively remove heat from the flywheel chamber during operation.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0008] A flywheel energy storage system includes a rotor assembly and a housing. The rotor assembly includes a shaft and a rotor. The rotor is coaxially mounted on the shaft. The upper end of the shaft passes through the housing and is sealed and rotatably connected to the housing. The lower end of the shaft is rotatably connected to the housing. The rotor is located within the housing. An upper water collecting ring is provided on the upper edge of the rotor, and a lower water collecting ring is provided on the lower edge of the rotor. Multiple water-cooling pipes are uniformly arranged along the circumference of the rotor on its outer wall surface. The upper ends of the water-cooling pipes are connected to the upper water collecting ring, and the lower ends of the water-cooling pipes are connected to the lower water collecting ring. A first water channel and a second water channel are provided in the shaft. The upper ends of the first water channel and the upper ends of the second water channel extend to the upper end face of the shaft. The lower end of the first water channel extends to the bottom of the rotor. The lower end of the first water channel is connected to the lower water collecting ring through a first water collecting pipe. The lower end of the second water channel extends to the top of the rotor. The second water channel is connected to the upper water collecting ring through a second water collecting pipe.

[0009] Optionally, the lower end of the first water channel is connected to the lower water collection ring through at least two first water collection pipes. One end of all the first water collection pipes is connected to the lower end of the first water channel, and the other end of all the first water collection pipes is evenly distributed in the circumferential direction of the lower water collection ring and connected to the lower water collection ring.

[0010] Optionally, the first water channel is set along the axis of rotation.

[0011] Optionally, in the rotating shaft, at least two second water channels are evenly provided around the first water channel. The axes of all the second water channels are parallel to the axis of the rotating shaft. The lower end of each second water channel is connected to the upper water collection ring through a second water collection pipe. The connection points of all the second water collection pipes and the upper water collection ring are evenly distributed around the upper water collection ring.

[0012] Optionally, the connection point between the first water collection pipe and the lower water collection ring is located at the midpoint of the connection points between two adjacent water cooling pipes and the lower water collection ring.

[0013] Optionally, the connection point between the second water collection pipe and the upper water collection ring is located at the midpoint between the connection points of two adjacent water cooling pipes and the upper water collection ring.

[0014] Optionally, both the second water collection pipe and the first water collection pipe are straight pipes, with the axis of the second water collection pipe intersecting the axis of the rotating shaft, and the axis of the first water collection pipe intersecting the axis of the rotating shaft.

[0015] Optionally, the rotor is cylindrical, and the upper and lower water collecting rings are circular. The upper water collecting ring is clamped on the upper edge of the rotor, and the lower water collecting ring is clamped on the lower edge of the rotor.

[0016] Optionally, the flywheel energy storage system of this application also includes a motor, which is connected to the upper end of the rotating shaft and located outside the housing. The motor includes an electric motor or a generator.

[0017] This application also provides a cooling method for the flywheel energy storage system described above, comprising the following process:

[0018] Cooling water is introduced into the first water channel. The cooling water in the first water channel flows sequentially through the first water collection pipe, the lower water collection ring, the water cooling pipe, the upper water collection ring, the second water collection pipe, and the second water channel to cool the shaft and rotor.

[0019] This application has the following beneficial effects:

[0020] In the flywheel energy storage system of this application, a cooling structure is set up to cool the rotor assembly shaft and the shaft itself. Specifically, the cooling structure includes a first water channel and a second water channel set in the shaft. When cooling water flows in the first water channel and the second water channel, the shaft can be cooled. The cooling structure also includes an upper water collecting ring, a lower water collecting ring, and water-cooling pipes. The lower water collecting ring can distribute the cooling water provided by the first water channel through the first water collecting pipe to each water-cooling pipe. As the main structure for cooling the rotor, the water-cooling pipes can absorb heat from the rotor and the space around the rotor. The upper water collecting ring can collect the cooling water after heat exchange from each water-cooling pipe and discharge it into the second water channel through the second water collecting pipe, thereby realizing the flow of cooling water in the cooling structure. The lower end of the first water channel extends to the bottom of the rotor, while the lower water collecting ring is located at the lower edge of the rotor; therefore, the first water collecting pipe is inclined. The lower end of the second water channel extends to the top of the rotor, while the upper water collecting ring is located at the upper edge of the rotor; therefore, the second water collecting pipe is inclined. Since both the first and second water collecting pipes are inclined, when the rotor rotates, the first water collecting pipe can cool the area below the lower surface of the rotor, and the second water collecting pipe can cool the area above the upper surface of the rotor. Therefore, the flywheel energy storage system of this application can effectively cool the rotor. Furthermore, in this application, the upper water collecting ring, water-cooling pipe, and lower water collecting ring form a squirrel-cage structure that wraps around the outside of the rotor. The inclined tension provided by the first and second water collecting pipes ensures the strength of the cooling structure in the flywheel energy storage system of this application, enabling it to withstand high rotational speeds. As can be seen from the structure of the flywheel energy storage system in this application, the rotor structure remains intact without damage. Therefore, the improvements in this application do not affect the rotor's strength. Although a first water channel and a second water channel are added to the shaft, their proximity to the shaft's axis minimizes their impact on the shaft's strength. In summary, this application, without affecting the overall rotor structure and strength and with minimal impact on the shaft's strength, effectively transfers heat from the flywheel chamber (i.e., the inner cavity of the housing) to the outside by adding a cooling structure within the flywheel energy storage system. This maintains the temperature within the flywheel chamber at a preset temperature, allowing the rotor assembly to operate in a suitable environment. This ensures both the charging and discharging efficiency of the rotor assembly and the safe operation of the entire flywheel energy storage system. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 is an overall structural diagram of a flywheel energy storage system in one embodiment of this application;

[0023] Figure 2 is an internal structural diagram of the flywheel energy storage system in the embodiment shown in Figure 1;

[0024] Figure 3 is an internal structural diagram of a flywheel energy storage system in another embodiment of this application;

[0025] Wherein: 1 is the housing; 2 is the rotor; 3 is the motor; 4 is the shaft; 5 is the first water channel; 501 is the first water channel interface; 6 is the second water channel; 601 is the second water channel interface; 7 is the second water collection pipe; 8 is the upper water collection ring; 9 is the water cooling pipe; 10 is the lower water collection ring; 11 is the first water collection pipe. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0027] Referring to Figures 1, 2, and 3, the flywheel energy storage system of this embodiment includes a rotor assembly and a housing 1. The rotor assembly includes a shaft 4 and a rotor 2. The rotor 2 is coaxially mounted on the shaft 4. The upper end of the shaft 4 passes through the housing 1 and is sealed and rotatably connected to the housing 1, thus forming a sealed chamber (also called a flywheel chamber) inside the housing 1. A vacuum is drawn inside the housing 1 to create a vacuum state inside the housing 1. The lower end of the shaft 4 is rotatably connected to the housing 1, and the rotor 2 is located inside the housing 1. An upper water collecting ring 8 is provided on the upper edge of the rotor 2, and a lower water collecting ring 10 is provided on the lower edge of the rotor 2. Multiple water-cooling pipes 9 are evenly arranged along the circumference of the rotor 2 on the outer wall surface of the rotor 2. The upper end of the water-cooling pipe 9 is connected to the upper water collecting ring 8, and the lower end of the water-cooling pipe 9 is connected to the lower water collecting ring 10. Thus, the lower water collecting ring 10, the upper water collecting ring 8, and the water cooling pipe 9 together form a squirrel cage structure. This structure has high load-bearing capacity and high stability, thereby ensuring the overall stability of the flywheel energy storage system of this application. The rotating shaft 4 is provided with a first water channel 5 and a second water channel 6. The upper end of the first water channel 5 and the upper end of the second water channel 6 extend to the upper end face of the rotating shaft 4. The lower end of the first water channel 5 extends to the lower part of the rotor 2. The lower end of the first water channel 5 is connected to the lower water collecting ring 10 through a first water collecting pipe 11. At this time, the first water collecting pipe 11 is in an inclined state. The lower end of the second water channel 6 extends to the upper part of the rotor 2. The second water channel 6 is connected to the upper water collecting ring 8 through a second water collecting pipe 7. At this time, the second water collecting pipe 7 is in an inclined state. In this embodiment of the flywheel energy storage system, although the interior of the casing 1 is a vacuum, a complete vacuum is impossible in practice. Therefore, some gas will inevitably exist within the cavity of the casing 1. In this embodiment, both the first water collection pipe 11 and the second water collection pipe 7 are inclined. When the rotor 2 rotates, the first water collection pipe 11 rotates below the lower surface of the rotor 2, cooling the area below the lower surface of the rotor 2. The second water collection pipe 7 rotates above the upper surface of the rotor 2, cooling the area above the upper surface of the rotor 2. This achieves cooling of both the upper and lower surfaces of the rotor 2. Furthermore, the inclined nature of both the first and second water collection pipes 11 and 7 facilitates the movement of air bubbles during cooling, ultimately allowing them to escape and significantly reducing the likelihood of airlock formation, thus improving the cooling effect. In addition, in this embodiment, the first and second water collection pipes 11 and 7 can be used to stretch the aforementioned squirrel-cage structure, ensuring the strength, integrity, and stability of the entire cooling structure. In this embodiment, since both the first water channel 5 and the second water channel 6 are located inside the rotating shaft 4, the cooling water can cool the rotating shaft 4 when it flows in the first water channel 5 and the second water channel 6.Furthermore, since this application can cool the shaft 4, the heat in the rotor 2 (mainly the part of the rotor 2 near the shaft 4) can be transferred to the shaft 4 through heat transfer. Therefore, this application can also indirectly cool the interior of the rotor 2 using the first water channel 5 and the second water channel 6. In this embodiment, the lower water collecting ring 10, the upper water collecting ring 8, and the water-cooling pipe 9 together form a squirrel-cage structure. This squirrel-cage structure is located on the outer edge of the rotor 2, thus enabling cooling of the outer edge of the rotor 2 (especially the sidewall portion). As can be seen from the above scheme of this embodiment, this embodiment can cool the center, outer edge, upper surface, and lower surface of the rotor 2, exhibiting a good cooling effect.

[0028] The cooling method for the flywheel energy storage system described in the above embodiments of this application includes the following process:

[0029] Cooling water is introduced into the first water channel 5. The cooling water in the first water channel 5 flows sequentially through the first water collection pipe 11, the lower water collection ring 10, the water-cooled pipe 9, the upper water collection ring 8, the second water collection pipe 7, and the second water channel 6. The cooling water entering from the first water channel 5 will flow from top to bottom in the rotating shaft 4 along the first water channel 5. When it flows to the lower end of the first water channel 5, the cooling water flows through the first water collection pipe 11 to the lower water collection ring 10. The cooling water entering the lower water collection ring 10 is distributed by the lower water collection ring 10 and enters the lower end of each water-cooled pipe 9 and flows from bottom to top along the water-cooled pipe 9. Then the cooling water flows out from the upper end of the water-cooled pipe 9 and enters the upper water collection ring 8 for collection. Then it enters the second water channel 6 through the second water collection pipe 7. Then the cooling water flows out in the rotating shaft 4 along the second water channel 6. Through the above process, the cooling of the rotating shaft 4 and the rotor 2 is achieved. Since the cooling water enters the entire cooling structure through the first water channel 5 and flows out through the second water channel 6 after absorbing heat, the temperature of the cooling water in the first water channel 5 is lower than the temperature of the cooling water in the second water channel 6. In the entire cooling structure, along the flow path of the cooling water, the first water manifold 11 is located upstream of the second water manifold 7; therefore, the temperature of the cooling water in the first water manifold 11 is lower than the temperature of the cooling water in the second water manifold 7.

[0030] As an optional implementation of this application, in this embodiment, the first water channel 5 is arranged along the axis of the rotating shaft 4. Since the first water channel 5 is coaxial with the rotating shaft 4, the vibration of the rotating shaft 4 during rotation can be reduced.

[0031] As an optional implementation of this application, in this embodiment, the lower end of the first water channel 5 is connected to the lower water collection ring 10 through at least two first water collection pipes 11. One end of all the first water collection pipes 11 is connected to the lower end of the first water channel 5, and the other end of all the first water collection pipes 11 is evenly distributed in the circumferential direction of the lower water collection ring 10 and connected to the lower water collection ring 10. The purpose of this arrangement is that all the first water collection pipes 11 are evenly distributed in the circumferential direction of the rotating shaft 4, and the rotation center of all the first water collection pipes 11 is concentric with the rotating shaft 4, which can reduce the vibration when the rotating shaft 4 rotates.

[0032] As an optional implementation of this application, in this embodiment, at least two second water channels 6 are evenly provided around the first water channel 5 in the rotating shaft 4. The axes of all second water channels 6 are parallel to the axis of the rotating shaft 4. The lower end of each second water channel 6 is connected to the upper water collection ring 8 through a second water collecting pipe 7. The connection points of all second water collecting pipes 7 and the upper water collection ring 8 are evenly distributed around the upper water collection ring 8. The purpose of this arrangement is that all the second water channels 6 are evenly distributed around the rotating shaft 4, and the rotation center of all the second water channels 6 is concentric with the rotating shaft 4, which can reduce the vibration when the rotating shaft 4 rotates.

[0033] As an optional implementation of this application, referring to Figure 3, in this embodiment, the connection point between the first water collection pipe 11 and the lower water collection ring 10 is located at the midpoint of the connection points between two adjacent water cooling pipes 9 and the lower water collection ring 10. This structural design is intended to prevent the cooling water transported by the first water collection pipe 11 from preferentially flowing away from the water cooling pipe 9 closer to the first water collection pipe 11 in the lower water collection ring 10, resulting in uneven water distribution in the lower water collection ring 10. Consequently, the cooling effect is asymmetrical in the circumferential direction of the rotor 2. Since the material used to prepare the rotor 2 has the property of thermal expansion and contraction, the thermal expansion of the higher temperature area on the rotor 2 will be greater than that of the lower temperature area. This will lead to the asymmetrical shape of the rotor 2, which in turn will increase the eccentricity between the center of mass of the rotor 2 and the center of the shaft 4, resulting in the rotor 2 rotating unstablely at high speed. On the other hand, in the above structure, the water flowing out from the first water collection pipe 11 flows into the two adjacent water-cooling pipes 9 at basically the same speed. This ensures that the water temperature of the cooling water is basically symmetrical on both sides of each first water collection pipe 11, which means that the density distribution of the cooling water in the squirrel-cage structure is also basically symmetrical. Since the eccentricity of the center of mass of the rotor 2 when it rotates at high speed will cause the rotor 2 to generate large vibrations when it rotates with the shaft 4, the above-mentioned structural design in this embodiment greatly reduces the uneven mass distribution of the entire cooling water network (referring to the distribution structure of the cooling water in the squirrel-cage structure, i.e., after removing all the pipes in the squirrel-cage structure, the shape of the remaining water is the same as the shape of the squirrel-cage structure, and the structure of the cooling water at this time is called the cooling water network, and the shape of the cooling water network is also squirrel-cage) caused by the uneven density of the cooling water in the squirrel-cage structure, which leads to an increased eccentricity between the center of mass of the squirrel-cage structure and the center of the shaft 4, resulting in the instability of the rotor 2 at high speed.

[0034] As an optional implementation scheme of this application, referring to Figure 3, in this embodiment, the connection point between the second water collection pipe 7 and the upper water collection ring 8 is located at the midpoint of the connection points between two adjacent water cooling pipes 9 and the upper water collection ring 8. The function and purpose of the structural design in this embodiment are the same as those in the above embodiment, where the connection point between the first water collection pipe 11 and the lower water collection ring 10 is located at the midpoint of the connection points between two adjacent water cooling pipes 9 and the lower water collection ring 10, and will not be repeated here.

[0035] As an optional implementation of this application, in this embodiment, both the second water collection pipe 7 and the first water collection pipe 11 are straight pipes. The axis of the second water collection pipe 7 intersects the axis of the rotating shaft 4, and the axis of the first water collection pipe 11 intersects the axis of the rotating shaft 4. In this embodiment, the above-mentioned design of the second water collection pipe 7 and the first water collection pipe 11 ensures that during the rotation of the rotor 2, the second water collection pipe 7 and the first water collection pipe 11 are mainly subjected to tension or pressure, avoiding bending moments. This prevents bending of the second water collection pipe 7 and the first water collection pipe 11 in the plane of rotation when the rotor 2 rotates at high speed. This also avoids significant additional stress on the connection points at both ends of the second water collection pipe 7 and the first water collection pipe 11, preventing a decrease in reliability at the connection points. Furthermore, this design also avoids an increased eccentricity between the center of mass of the overall structure formed by the second water collection pipe 7, the first water collection pipe 11, and their internal cooling water and the center of the rotating shaft 4, which could lead to instability during high-speed rotation of the rotor 2.

[0036] As an optional implementation of this application, in this embodiment, the rotor 2 is cylindrical in shape, and correspondingly, the upper water collecting ring 8 and the lower water collecting ring 10 are circular in shape. The upper water collecting ring 8 is clamped on the upper edge of the rotor 2, and the lower water collecting ring 10 is clamped on the lower edge of the rotor 2.

[0037] As an optional implementation of this application, in this embodiment, the surfaces of the upper water collecting ring 8, the lower water collecting ring 10, and the water-cooling pipe 9 that contact the rotor 2 are configured as curved surfaces adapted to the shape of the contact area with the rotor 2. This increases the contact area between the upper water collecting ring 8, the lower water collecting ring 10, and the water-cooling pipe 9 and the rotor 2, thereby improving the cooling effect on the rotor 2. For example, the side of the water-cooling pipe 9 facing the sidewall of the rotor 2 can be configured as a cylindrical surface with the same curvature as the sidewall of the rotor 2. This forms a surface contact between the water-cooling pipe 9 and the sidewall of the rotor 2, improving the heat exchange effect.

[0038] As an optional implementation of this application, referring to FIG1, in this embodiment, the flywheel energy storage system of this application further includes a motor 3, which is connected to the upper end of the rotating shaft 4 and located outside the housing 1. The motor 3 can be an electric motor or a generator.

[0039] Example

[0040] Referring to Figure 3, the flywheel energy storage system of this embodiment includes a rotor assembly, a housing 1, and a motor. The rotor assembly includes a shaft 4 and a rotor 2. The rotor 2 is coaxially mounted on the shaft 4. The upper end of the shaft 4 passes through the housing 1 and is sealed and rotatably connected to the housing 1. The lower end of the shaft 4 is rotatably connected to the housing 1. The rotor 2 is located in the housing 1. An upper water collecting ring 8 is provided on the upper edge of the rotor 2, and a lower water collecting ring 10 is provided on the lower edge of the rotor 2. Twelve water-cooling pipes 9 are evenly arranged along the circumference of the outer wall of the rotor 2. The upper end of the water-cooling pipes 9 communicates with the upper water collecting ring 8, and the lower end of the water-cooling pipes 9 communicates with the lower water collecting ring 10. The shaft 4 has one first water channel 5 and two second water channels 6. The upper end of the first water channel 5 and the upper end of the second water channels 6 extend to the upper end face of the shaft 4. The first water channel 5 extends along the shaft 4. The first water channel 5 is symmetrically distributed on both sides of the first water channel 5, with its axis parallel to the axis of the rotating shaft 4. The lower end of the first water channel 5 extends below the rotor 2 and is connected to the lower water collection ring 10 via two first water collection pipes 11. These two first water collection pipes 11 are symmetrically distributed on both sides of the axis of the rotating shaft 4, and their connection points with the lower water collection ring 10 are symmetrically distributed around the circumference of the lower water collection ring 10. The lower end of the second water channel 6 extends above the rotor 2 and is connected to the upper water collection ring 8 via two second water collection pipes 7. These two second water collection pipes 7 are symmetrically distributed on both sides of the axis of the rotating shaft 4, and their connection points with the upper water collection ring 8 are symmetrically distributed around the circumference of the upper water collection ring 8. The connection point between the first water collection pipe 11 and the lower water collection ring 10 is located at the midpoint of the connection points between two adjacent water cooling pipes 9 and the lower water collection ring 10. The connection point between the second water collecting pipe 7 and the upper water collecting ring 8 is located at the midpoint of the connection points between two adjacent water-cooling pipes 9 and the upper water collecting ring 8. Along the axial direction of the rotating shaft 4, the included angle between the second water collecting pipe 7 and the first water collecting pipe 11 is 90°. Both the second water collecting pipe 7 and the first water collecting pipe 11 are straight pipes. The axis of the second water collecting pipe 7 intersects the axis of the rotating shaft 4, and the axis of the first water collecting pipe 11 intersects the axis of the rotating shaft 4. The rotor 2 is cylindrical, and the upper water collecting ring 8 and the lower water collecting ring 10 are both circular. The upper water collecting ring 8 is clamped around the upper edge of the rotor 2, and the lower water collecting ring 10 is clamped around the lower edge of the rotor 2. The motor is connected to the upper end of the rotating shaft 4 and is located outside the housing 1. Correspondingly, in this embodiment, a first water channel interface 501 is provided at the water inlet end of the first water channel 5, and a second water channel interface 601 is provided at the water outlet end of the second water channel 6. Since the temperature of the cooling water in the first water channel 5 is lower than the temperature of the cooling water in the second water channel 6, the temperature of the cooling water in the first water channel interface 501 is lower than the temperature of the cooling water in the second water channel interface 601.

[0041] The cooling method for the flywheel energy storage system in this embodiment includes the following process:

[0042] Cooling water is introduced into the first water channel 5. At the lower end of the first water channel 5, the cooling water splits into two paths, which are simultaneously fed into the lower water collection ring 10 through two first water collection pipes 11. The cooling water in the lower water collection ring 10 flows symmetrically on both sides of the two connecting points (i.e., the connection points between the two first water collection pipes 11 and the lower water collection ring 10). Because the two connecting points (i.e., the connection points between the two first water collection pipes 11 and the lower water collection ring 10) are symmetrical, the temperature of the cooling water in the lower water collection ring 10 is also symmetrical (i.e., about the axis of the two first water collection pipes 11 and the rotation). The cooling water flows upward along the water-cooling pipe 9 into the upper water-collecting ring 8. Since the temperature of the cooling water in the lower water-collecting ring 10 is symmetrical, and the connection point between the first water-collecting pipe 11 and the lower water-collecting ring 10 is located at the midpoint of the connection points between two adjacent water-cooling pipes 9 and the lower water-collecting ring 10, and the connection point between the second water-collecting pipe 7 and the upper water-collecting ring 8 is located at the midpoint of the connection points between two adjacent water-cooling pipes 9 and the upper water-collecting ring 8, the temperature of the cooling water in the upper water-collecting ring 8 is also symmetrical (i.e., symmetrical about the plane containing the axes of the two first water-collecting pipes 11 and the axis of the rotating shaft 4). The cooling water in the upper water-collecting ring 8 is then transported along the two second water-collecting pipes 7 to the two second water channels 6, and discharged from the second water channels 6. Since the angle between the second water-collecting pipe 7 and the first water-collecting pipe 11 along the axis of the rotating shaft 4 is 90°, the temperature of the cooling water in the upper water-collecting ring 8 at the points connected to the two second water-collecting pipes 7 is basically the same, therefore the cooling water temperatures in the two second water-collecting pipes 7 are the same. As can be seen from the above, the design structure of this embodiment greatly reduces the degree of eccentricity of the flywheel energy storage system during rotation, which is beneficial to the stable operation of the rotor assembly and cooling structure at high speed.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A flywheel energy storage system, characterized in that, The system includes a rotor assembly and a housing (1). The rotor assembly includes a rotating shaft (4) and a rotor (2). The rotor (2) is coaxially mounted on the rotating shaft (4). The upper end of the rotating shaft (4) passes through the housing (1) and is sealed and rotatably connected to the housing (1). The lower end of the rotating shaft (4) is rotatably connected to the housing (1). The rotor (2) is located in the housing (1). An upper water collecting ring (8) is provided on the upper edge of the rotor (2), and a lower water collecting ring (10) is provided on the lower edge of the rotor (2). Multiple water-cooling pipes (9) are evenly provided on the outer wall of the rotor (2) along the circumference of the rotor (2). The upper end of the water-cooling pipe (9) is connected to the upper water collecting ring (8). The lower end of the water-cooling pipe (9) is connected to the lower water collection ring (10); the rotating shaft (4) is provided with a first water channel (5) and a second water channel (6). The upper end of the first water channel (5) and the upper end of the second water channel (6) extend to the upper end face of the rotating shaft (4). The lower end of the first water channel (5) extends to the lower part of the rotor (2). The lower end of the first water channel (5) is connected to the lower water collection ring (10) through a first water collection pipe (11). The lower end of the second water channel (6) extends to the upper part of the rotor (2). The second water channel (6) is connected to the upper water collection ring (8) through a second water collection pipe (7). Both the second water collection pipe (7) and the first water collection pipe (11) are straight pipes. The axis of the second water collection pipe (7) intersects the axis of the rotating shaft (4), and the axis of the first water collection pipe (11) intersects the axis of the rotating shaft (4).

2. The flywheel energy storage system according to claim 1, characterized in that, The lower end of the first water channel (5) is connected to the lower water collection ring (10) through at least two first water collection pipes (11). One end of all the first water collection pipes (11) is connected to the lower end of the first water channel (5), and the other end of all the first water collection pipes (11) is evenly distributed in the circumference of the lower water collection ring (10) and connected to the lower water collection ring (10).

3. The flywheel energy storage system according to claim 1, characterized in that, The first water channel (5) is set along the axis of the rotating shaft (4).

4. The flywheel energy storage system according to claim 3, characterized in that, In the rotating shaft (4), at least two second water channels (6) are evenly provided around the first water channel (5). The axis of all the second water channels (6) is parallel to the axis of the rotating shaft (4). The lower end of each second water channel (6) is connected to the upper water collection ring (8) through a second water collection pipe (7). The connection points of all the second water collection pipes (7) and the upper water collection ring (8) are evenly distributed around the upper water collection ring (8).

5. A flywheel energy storage system according to claim 1, characterized in that, The connection point between the first water collection pipe (11) and the lower water collection ring (10) is located at the midpoint of the connection points between the two adjacent water cooling pipes (9) and the lower water collection ring (10).

6. The flywheel energy storage system according to claim 1, characterized in that, The connection point between the second water collection pipe (7) and the upper water collection ring (8) is located at the midpoint of the connection points between the two adjacent water cooling pipes (9) and the upper water collection ring (8).

7. The flywheel energy storage system according to claim 1, characterized in that, The rotor (2) is cylindrical in shape, and the upper water collecting ring (8) and the lower water collecting ring (10) are circular in shape. The upper water collecting ring (8) is clamped on the upper edge of the rotor (2), and the lower water collecting ring (10) is clamped on the lower edge of the rotor (2).

8. A flywheel energy storage system according to claim 1, characterized in that, It also includes a motor (3), which is connected to the upper end of the rotating shaft (4) and located outside the housing (1). The motor (3) includes an electric motor or a generator.

9. A cooling method for the flywheel energy storage system according to any one of claims 1-8, characterized in that, The process includes the following: Cooling water is introduced into the first water channel (5). The cooling water in the first water channel (5) flows through the first water collection pipe (11), the lower water collection ring (10), the water cooling pipe (9), the upper water collection ring (8), the second water collection pipe (7), and the second water channel (6) in sequence to achieve cooling of the rotating shaft (4) and the rotor (2).

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