Motor with stator assembly immersed in cooling liquid for heat dissipation

Abstract

The invention discloses a motor with a stator assembly immersed in cooling liquid for heat dissipation, belongs to the technical field of motor heat dissipation, and solves the problem of non-uniform heat dissipation in the stator assembly of the current motor. The design scheme that the stator assembly is completely immersed in the insulating and heat-conducting cooling liquid is adopted, corresponding sealing isolation measures are adopted, the stator assembly and the rotor are subjected to dry-wet separation, the rotor can still run in gas, meanwhile, the slidable sealing flange is designed, the size of a sealed cavity of the cooling liquid is variable, and the sealing effect is good. And leakage caused by pressure increase due to thermal expansion of the cooling liquid is avoided. The method is suitable for normal operation and loss reduction of the motor needing to be maintained when the interior is overheated during high-speed rotation of the motor.

Description

Technical Field

[0001] The invention belongs to the field of motor heat dissipation, and in particular relates to a motor with a stator component immersed in coolant for heat dissipation. Background Art

[0002] Any motor, including generators, requires a heat dissipation system to transfer the heat generated by the motor's stator and rotor to the outside when it is working, to achieve a balance between the heat generated by the motor and the amount of heat dissipated, and to stabilize the internal temperature of the motor within the range allowed for normal operation of the motor. Common heat dissipation methods include natural air cooling, external circulation air cooling with an external shaft fan, internal circulation air cooling with an external forced fan, and circulating liquid cooling. Since the thermal conductivity of the coolant is more than an order of magnitude higher than that of air, the low-temperature coolant of the circulating liquid cooling can quickly take away the heat generated by the motor when it flows through the motor housing or the pipeline of the stator assembly. The heat dissipation is much greater than that of the air cooling method, and the heat dissipation efficiency is also higher. Circulating liquid cooling is often used on high-power motors or generators.

[0003] like Figure 1 The figure shows one of the existing liquid cooling structures. The coolant flows through the threaded heat exchange pipeline outside the motor stator assembly, and the heat exchange area between the main heat-generating components, namely the stator assembly, is limited, resulting in the inability of the stator winding end and the inner hole of the stator core to directly exchange heat with the coolant. Most of the heat at the winding end needs to be transferred to the liquid cooling system through heat conduction, and its path must pass through the enameled wire, insulation paper, and stator core in the wire slot. The insulation paper is a material with a very low thermal conductivity and is the bottleneck of the heat conduction path. Therefore, it will inevitably cause heat accumulation at the winding end, and the winding end becomes the area with the highest temperature inside the motor. Air-cooled motors have poor heat dissipation efficiency due to the low thermal conductivity of air. Under the same heat dissipation effect, the energy consumption is higher, which affects the overall efficiency of the motor. All these existing cooling methods make the temperature of different parts of the motor's stator assembly very uneven, and the high-temperature parts are prone to become failure points, reducing the overall reliability of the motor. Summary of the invention

[0004] The technical problem to be solved by the present invention is that under various air cooling and liquid cooling methods for cooling the motor in the prior art, the temperatures of different parts of the stator assembly are very uneven, and the high-temperature parts easily become failure points, reducing the overall reliability of the motor.

[0005] The motor with a coolant-immersed stator assembly for heat dissipation disclosed in the present invention includes, in addition to the motor rotor and the stator assembly consisting of a stator core and a stator winding, a motor housing wrapped around the stator assembly and a bearing supporting the motor rotor; in particular, a closed cavity is separately configured for the stator assembly of the motor in the motor housing, and the closed cavity is filled with coolant for immersing the stator core and the winding; the coolant must have good insulation performance and high thermal conductivity, and must not affect the normal operation of the rotor.

[0006] Preferably, the coolant is commonly used transformer oil because its insulation and thermal conductivity can meet the requirements.

[0007] Optionally, the enclosed cavity is externally connected to a cavity structure whose volume can change when the internal pressure changes due to thermal expansion and contraction of the coolant, so as to avoid leakage of the coolant when the pressure is high.

[0008] Furthermore, a cylindrical tube is installed in the inner hole of the stator core, and the cylindrical tube is between the gap between the stator core and the rotor; the closed cavity is surrounded by the outer surface of the cylindrical tube, the inner hole surface of the motor housing, and two sealing flanges at both ends perpendicular to the two cylindrical surfaces; the material property of the cylindrical tube must be non-magnetic; Optionally, the cylindrical tube is made of a non-magnetic metal. Since the surface of the metal cylindrical tube wall may generate eddy currents and cause losses, the thinner the cylindrical tube made of metal material is, the better.

[0009] Optionally, the sealing flange is made of non-metallic material.

[0010] Preferably, the cylindrical tube is a carbon fiber tube, because although the high temperature resistance of the carbon fiber tube is not as good as that of metal materials, it can meet the actual use conditions in many cases, and the carbon fiber tube is insulated and non-magnetic, so it will not cause eddy current loss on the surface like the metal thin-walled tube.

[0011] Furthermore, the sealing flange is made of metal material; O-rings are respectively arranged on the inner hole surface and the outer surface of the sealing flange at the axial ends of the cylindrical tube to ensure that the sealing flange can move along the axial direction without affecting the sealing of the closed cavity of the coolant. This technical solution makes the volume of the closed cavity of the coolant variable to adapt to the volume change caused by the thermal expansion of the coolant, keep the pressure inside the closed cavity unchanged, and prevent the liquid from leaking out. Because the temperature of the coolant rises when the motor is running, the volume expands, the pressure increases, and the sealing flange is pushed outward, the sealing flange moves along the axial direction, the volume of the closed cavity increases, and the pressure decreases until the internal and external pressures are balanced. The pressure inside the closed cavity of the coolant is the same as the pressure outside. As long as the O-ring is closed normally, the coolant will not leak out.

[0012] Preferably, air bearings are disposed at both ends of the rotor shaft of the motor.

[0013] In summary, the present invention completely immerses the stator assembly in an insulating and heat-conducting coolant, so that all parts of the stator assembly are cooled evenly at the same time, reducing the thermal resistance or temperature difference between the stator assembly and the heat dissipation medium, so that the heat of the stator core and windings is quickly and efficiently transferred to other heat dissipation media, and then the motor housing is combined with conventional liquid cooling or external air cooling to efficiently transfer the heat generated by the motor stator assembly during operation to the motor housing. The present invention achieves a high heat dissipation effect with a simple and ingenious heat dissipation method, while avoiding the problem of additional energy consumption caused by the relative movement between the motor rotor and the coolant in the closed cavity, and can well solve the consequences of internal heating during the operation of ultra-high-speed motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the motor structure of the threaded tube coolant heat dissipation stator assembly Figure 2 Schematic diagram of the internal structure of the motor with the stator assembly immersed in coolant to dissipate heat Figure 3 Axonometric diagram of the stator assembly immersed in coolant in a closed cavity Among them Figure 2 The names corresponding to the numbers in Fig. 3 are: 1 rotor; 2 stator core; 3 stator winding; 4 motor housing; 5 bearing; 6 coolant; 7 carbon fiber tube; 8 sealing flange; 9 O-ring A; 10 O-ring B Example

[0015] The motor disclosed in this embodiment, which dissipates heat by immersing the stator assembly in the coolant, adopts a design scheme in which the stator assembly is completely immersed in the insulating and heat-conductive coolant, and takes corresponding sealing and isolation measures to separate the stator assembly from the rotor in dry and wet conditions, while the rotor can still operate in the gas. At the same time, a sliding sealing flange is designed to make the volume of the enclosed cavity of the coolant variable, thereby preventing the coolant from leaking out due to the pressure increase caused by the thermal expansion of the coolant.

[0016] like Figure 2 and Figure 3 As shown, the motor with a coolant immersed stator assembly for heat dissipation disclosed in this embodiment includes a rotor 1 of the motor and a stator assembly of the motor composed of a stator core 2 and a stator winding 3, and also includes a motor housing 4 wrapped outside the stator assembly and a bearing 5 supporting the rotor 1. In particular, a closed cavity is separately configured for the stator assembly of the motor, and a coolant 6 for immersing the stator assembly is encapsulated in the closed cavity without affecting the normal operation of the rotor.

[0017] The coolant 6 must have good insulation performance and high thermal conductivity. In this embodiment, ordinary transformer oil is selected because it can meet the requirements of actual use. Although the enclosed cavity can also be designed as an externally connected variable volume cavity structure, the enclosed cavity described in this embodiment is surrounded by the outer surface of a cylindrical tube 7 between the stator core 2 and the rotor 1, the inner hole surface of the motor housing 4, and a sealing flange 8 perpendicular to the two cylindrical surfaces; the cylindrical tube 7 is installed in the inner hole of the stator core 2.

[0018] The motor rotor 1 in this embodiment is provided with air bearings 5 ​​at both ends of the rotor shaft outside the stator assembly; the cylindrical tube 7 between the stator core and the air gap of the rotor must be made of a non-magnetic material; although the cylindrical tube 7 can also be made of a thin-walled metal material, the metal thin-walled tube will have losses caused by surface eddy currents, so in this embodiment, a carbon fiber tube 7 is used; although the carbon fiber tube is not as high-temperature resistant as metal, it can meet the actual use requirements in this embodiment and will not generate surface eddy current losses; although the sealing flange 8 can also be made of non-metallic material, the sealing flange in this embodiment is made of metal material, and an O-ring A9 is added on the inner surface of the sealing flange 8; an O-ring B10 is added on the outer surface of the sealing flange 8, and the sealing flange 8 can move along the axial direction without affecting the sealing of the closed cavity of the coolant.

[0019] The technical effect of this embodiment is as follows: since the stator assembly of the motor is completely immersed in the insulating and heat-conductive coolant, the temperatures of various parts of the stator assembly are evenly cooled at the same time, thereby reducing the thermal resistance or temperature difference between the stator assembly and the heat dissipation medium, so that the heat of the stator core and windings is quickly and efficiently transferred to other heat dissipation media, and the motor housing is combined with conventional liquid cooling or external air cooling to efficiently transfer the heat of the stator assembly during the operation of the motor to the motor housing.

[0020] According to the idea of ​​the present invention, after the coolant immerses the stator assembly, in order to solve the consequences of pressure caused by thermal expansion and contraction in the closed cavity, an external cavity structure can also be used to meet the cooling liquid leakage that may be caused by the internal pressure change of the cooling liquid closed cavity.

[0021] The present invention achieves a high heat dissipation effect with a simple and ingenious heat dissipation method, while avoiding the problem of additional energy consumption caused by the relative movement between the motor rotor and the coolant of the stator assembly. This is a good solution for the heat dissipation under ultra-high-speed rotation required by motors including those with air-suspended bearings supporting the rotor.

Claims

1. A motor with a stator assembly immersed in a coolant for heat dissipation, comprising a rotor of the motor and a stator assembly consisting of a stator core and a stator winding, and also comprising a motor housing wrapped outside the stator assembly and a bearing supporting the motor rotor; characterized in that: A closed cavity is separately configured for the stator assembly of the motor under the motor housing, and the closed cavity is filled with a coolant that immerses the stator core and the stator winding; the coolant must have both insulating and heat-conductive properties, and the coolant in the closed cavity of the stator assembly does not affect the normal operation of the rotor.

2. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 1, characterized in that: The cooling liquid is selected from commonly used transformer oil.

3. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 1, characterized in that: The enclosed cavity is also externally connected to a cavity structure with a variable volume to accommodate leakage of coolant caused by increased internal pressure of the enclosed cavity due to thermal expansion and contraction.

4. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 1, characterized in that: A cylindrical tube is installed in the inner hole of the stator core, and the cylindrical tube is located between the air gap between the stator assembly and the rotor; the closed cavity is surrounded by the outer surface of the cylindrical tube, the inner hole surface of the motor housing, and two sealing flanges at both ends perpendicular to the two cylindrical surfaces; the material of the cylindrical tube must be non-magnetic.

5. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 4, characterized in that: The sealing flange is made of non-metallic material.

6. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 4, characterized in that: The cylindrical tube is made of metal material.

7. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 4, characterized in that: The cylindrical tube is a carbon fiber tube.

8. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 7, characterized in that: The sealing flange is made of metal material; O-ring A and O-ring B are respectively arranged on the inner hole and outer surface of the sealing flange at both axial ends of the carbon fiber tube to ensure that the sealing flanges at both ends can move along the axial direction without affecting the sealing of the coolant closed cavity.

9. The motor with a stator assembly immersed in coolant for heat dissipation as claimed in claim 8, characterized in that: Air bearings are respectively arranged at both ends of the motor rotor shaft.

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