A motor and screw compressor

Abstract

The application provides a motor and a screw compressor, the screw compressor comprising a first screw, the first screw comprising a thick shaft section and a thin shaft section, the thick shaft section being provided with a thread structure, the motor comprising a rotor core, a bushing being fixedly arranged in the rotor core, the bushing being used for being fixed on the thin shaft section, the bushing being provided with a heat dissipation hole extending along an axial direction, the heat dissipation hole penetrating through the bushing, and the maximum distance between the outlet of the heat dissipation hole and the axis of the bushing being greater than the radius of the thick shaft section, so that the temperature of the rotor can be efficiently reduced, and the demagnetization of the permanent magnet caused by high temperature can be avoided.

Description

Technical Field

[0001] This invention belongs to the field of screw compressor technology, specifically relating to an electric motor and a screw compressor. Background Technology

[0002] Driven by the intelligent upgrading of industry, the application prospects of variable frequency screw compressors are showing unprecedented breadth and deep penetration. Their core advantage, permanent magnet motor technology, allows for variable frequency speed regulation based on load, effectively avoiding energy waste in low-load conditions compared to traditional fixed-frequency compressors. This makes them widely applicable in air compression and large-scale building refrigeration. Variable frequency screw compressors significantly reduce equipment size and weight, lower operating noise, and extend the service life of core components, thus achieving more economical total life-cycle costs in fluctuating gas consumption scenarios such as photovoltaic manufacturing and food processing. However, the risk of irreversible demagnetization of permanent magnet motors under high-temperature environments remains a bottleneck for practical applications. This can lead to a sharp drop in motor output torque and a 15%-30% decrease in efficiency, resulting in fluctuations in compressor supply pressure, frequent start-ups and shutdowns, or complete shutdowns. If not addressed promptly, this can cause localized overheating due to motor overload, carbonization of insulation materials, or short circuits in the windings, ultimately leading to electrical fires or equipment explosions.

[0003] Taking a semi-hermetic refrigeration screw compressor as an example, such as Figure 15 As shown, due to the extremely small air gap in the motor, the flow rate of refrigerant across the rotor core surface is minimal, resulting in poor rotor heat dissipation. Furthermore, permanent magnets can undergo irreversible demagnetization at high temperatures, affecting motor performance. In certain high-reliability applications, the performance impact caused by thermal demagnetization of the motor rotor's permanent magnets can lead to serious safety accidents.

[0004] Therefore, how to efficiently reduce the rotor temperature and prevent permanent magnets from demagnetizing due to high temperatures is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] Therefore, the present invention provides an electric motor and a screw compressor that can efficiently reduce the temperature of the rotor and prevent the permanent magnet from demagnetizing due to high temperature.

[0006] In a first aspect, the present invention provides an electric motor applied to a screw compressor. The screw compressor includes a first screw, which includes a thick shaft section and a thin shaft section. The thick shaft section is provided with a threaded structure. The electric motor includes a rotor core, and a bushing is fixedly disposed inside the rotor core. The bushing is used to fix the thin shaft section. The bushing is provided with a heat dissipation hole extending in the axial direction, which penetrates the bushing. The maximum distance between the outlet of the heat dissipation hole and the axis of the bushing is greater than the radius of the thick shaft section.

[0007] In some embodiments, the heat dissipation holes extend in a spiral shape around the axis of the bushing.

[0008] In some embodiments, the distance between the heat dissipation hole and the bushing gradually increases from the inlet of the heat dissipation hole to the outlet of the heat dissipation hole.

[0009] In some embodiments, the motor further includes a housing, the inner wall of which is provided with axially extending grooves.

[0010] In some embodiments, the bushing is formed by 3D printing.

[0011] A second aspect of the present invention also provides a screw compressor, including a motor, wherein the screw compressor further includes a first screw and a second screw, the second screw meshing with the first screw.

[0012] In some embodiments, the screw compressor further includes a support frame, the support frame having a bearing hole, a bearing being disposed in the bearing hole, and one end of the thick shaft section connected to the thin shaft section passing through the bearing; the outlet direction of the heat dissipation hole coincides with that of the bearing.

[0013] In some embodiments, the bearing includes an outer ring and an inner ring, with an annular gap between the outer ring and the inner ring, and the outlet direction of the heat dissipation hole is toward the annular gap.

[0014] In some embodiments, the support frame is provided with a through hole that extends through the support frame itself along the axial direction of the first screw, and there are at least two heat dissipation holes, with the outlet direction of some of the heat dissipation holes facing the through hole.

[0015] In some embodiments, there are multiple through holes, which are arranged around the bearing hole, and the bearing is interference-fitted into the bearing hole.

[0016] This invention provides heat dissipation holes on the bushing, allowing the refrigerant to dissipate heat from the rotor core as it flows through the bushing. Simultaneously, the refrigerant is less affected by the thick shaft section when flowing out of the heat dissipation holes, enabling faster flow and increasing the refrigerant's cooling efficiency on the rotor core. This effectively reduces the rotor temperature and prevents demagnetization of the permanent magnets due to high temperatures. Both the motor and screw compressor in this application are energy-saving refrigeration and air conditioning equipment. Attached Figure Description

[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] Figure 1 This is a cross-sectional schematic diagram of the motor portion of the screw compressor according to an embodiment of the present invention;

[0019] Figure 2 This is an embodiment of the present invention. Figure 1 Enlarged view of point B in the image;

[0020] Figure 3 This is an embodiment of the present invention. Figure 1 The right view;

[0021] Figure 4 This is an embodiment of the present invention. Figure 1 The left view;

[0022] Figure 5 This is a schematic diagram of the bushing according to an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of a bushing with heat dissipation holes having a spiral structure according to an embodiment of the present invention;

[0024] Figure 7 This is a radial sectional view of the bushing according to an embodiment of the present invention;

[0025] Figure 8 This is an embodiment of the present invention. Figure 7 Top view;

[0026] Figure 9 This is an embodiment of the present invention. Figure 7 A bottom view;

[0027] Figure 10 This is a first-view schematic diagram of the screw compressor motor portion according to an embodiment of the present invention;

[0028] Figure 11 This is a second-view schematic diagram of the screw compressor motor portion according to an embodiment of the present invention;

[0029] Figure 12 This is a cross-sectional view of the rotor core fixed on the bushing according to an embodiment of the present invention;

[0030] Figure 13 This is a first-view schematic diagram of an embodiment of the present invention with the bushing fixed on the thin shaft section and the rotor core fixed on the bushing.

[0031] Figure 14This is a second-view schematic diagram of an embodiment of the present invention where the bushing is fixed on the thin shaft section and the rotor core is fixed on the bushing;

[0032] Figure 15 This is a schematic diagram of the motor section of a screw compressor in the prior art;

[0033] The attached figures are labeled as follows:

[0034] 1. First screw; 2. Coarse shaft section; 3. Fine shaft section; 4. Bushing; 5. Rotor core; 6. Stator core; 7. Heat dissipation hole; 8. Groove; 9. Support frame; 10. Bearing hole; 11. Bearing. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0037] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0038] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0039] In semi-hermetic screw compressors, the motor air gap is extremely small, resulting in very low refrigerant flow across the rotor core surface. This leads to poor rotor heat dissipation, and the permanent magnets can undergo irreversible demagnetization at high temperatures, affecting motor performance. Furthermore, in certain high-reliability applications, the performance impact caused by thermal demagnetization of the permanent magnets in the motor rotor can lead to serious safety accidents.

[0040] To efficiently reduce rotor temperature and prevent permanent magnet demagnetization due to high temperatures, please refer to [reference needed]. Figure 1-14 As shown, the present invention provides an electric motor applied to a screw compressor. The screw compressor includes a first screw 1, which includes a thick shaft section 2 and a thin shaft section 3. The thick shaft section 2 is provided with a threaded structure. The motor includes a rotor core 5, and a bushing 4 is fixedly disposed inside the rotor core 5. The bushing 4 is used to fix the thin shaft section 3. The bushing 4 is provided with a heat dissipation hole 7 extending in the axial direction. The heat dissipation hole 7 penetrates the bushing 4, and the maximum distance between the outlet of the heat dissipation hole 7 and the axis of the bushing 4 is greater than the radius of the thick shaft section 2.

[0041] In a screw compressor, the motor shaft is an extension of the shaft of the first screw 1. The motor is matched according to the screw configuration. The motor itself does not have a dedicated shaft. Instead, it is fixed to the first screw 1 by the thin shaft section 3 of the first screw 1 and the bushing 4.

[0042] By fixing a bushing 4 inside the rotor core 5, the thin shaft section 3 is first fitted and fixed together with the rotor core 5. Furthermore, heat dissipation holes 7 are provided on the bushing 4, allowing the refrigerant to effectively cover the core area of ​​the permanent magnet in the rotor core 5 as it flows along the heat dissipation holes 7, forming a through-flow heat dissipation channel from the inside to the outside of the rotor. This significantly improves the heat dissipation efficiency of the rotor side (especially the permanent magnet), fundamentally reducing the risk of demagnetization of the permanent magnet due to insufficient heat dissipation. In the axial direction, heat dissipation holes 7 are opened on the bushing 4, extending axially with a maximum distance between the outlet and the axis of the bushing 4 greater than the radius of the thick shaft section 2. This ensures that the outlet position of the heat dissipation holes 7 avoids the area of ​​the thick shaft section 2, and the thin shaft section 3 extending beyond the thick shaft section 2 is not blocked by the thick shaft section 2. This reduces the resistance encountered by the airflow when flowing out of the heat dissipation holes 7, increases the airflow velocity, and further improves the heat exchange efficiency between the airflow and the bushing 4. The motor of this application belongs to the strategic emerging industry field and has energy-saving and environmentally friendly technical effects.

[0043] Preferred, such as Figure 6 As shown, the heat dissipation hole 7 extends in a spiral shape around the axis of the bushing 4.

[0044] The heat dissipation holes 7 extend spirally around the axis of the bushing 4, coordinating with the direction of motor rotation. When the motor rotates at high speed, the refrigerant flow direction is consistent with the rotation direction, which greatly improves the flow rate and heat exchange efficiency of the refrigerant in the heat dissipation holes 7; at the same time, the spiral structure extends the contact path and time between the refrigerant and the rotor core 5, enhancing the heat exchange effect and enabling more effective control of the permanent magnet's operating temperature.

[0045] Preferably, from the inlet of the heat dissipation hole 7 to the outlet of the heat dissipation hole 7, the distance between the heat dissipation hole 7 and the bushing 4 gradually increases.

[0046] From the inlet to the outlet, the distance between the heat dissipation hole 7 and the axis of the bushing 4 gradually increases, meaning that the heat dissipation hole 7 expands in a centrifugal direction. This structure utilizes the natural acceleration effect of centrifugal force to gradually accelerate the refrigerant during flow, resulting in a higher flow velocity at the outlet end and a stronger ability to remove heat. At the same time, the expansion structure avoids back pressure and backflow caused by the sudden narrowing of the flow channel at the outlet end, ensuring continuous unidirectional and efficient flow of refrigerant within the heat dissipation hole 7, further improving heat dissipation performance.

[0047] Preferred, such as Figure 1 , Figure 3 and Figure 10 , Figure 11 As shown, the motor also includes a housing, and the inner wall of the housing is provided with an axially extending groove 8.

[0048] The inner wall of the housing is provided with axially extending grooves 8, which provide additional flow channels and heat exchange area for the refrigerant on the housing side. The grooves 8 and the heat dissipation holes 7 of the bushing 4 form a dual-path collaborative heat dissipation system of "rotor inside + housing inside": the heat dissipation holes 7 of the bushing 4 are responsible for precise cooling of the rotor side (the core area of ​​the permanent magnet), while the housing grooves 8 are responsible for expanding the refrigerant coverage on the stator side. The two complement each other, which greatly improves the overall heat dissipation capacity of the motor and avoids the defects of traditional designs that rely only on the housing flow channels to cool the stator and have a weak refrigerant flow on the rotor side.

[0049] The stator core 6 is fixed to the inner wall of the casing, and the refrigerant flows through the groove 8 to cool the stator core 6.

[0050] Preferred, such as Figure 6 As shown, the bushing 4 is formed by 3D printing.

[0051] The bushing 4 is formed using metal 3D printing (selective laser melting, SLM) technology. A high-precision laser beam melts AlSi10Mg aluminum alloy powder layer by layer to construct the rotor bushing 4. The laser power, scanning speed, and powder layer thickness (0.03-0.05mm) are precisely controlled to directly form the internal spiral flow channel, ensuring that the geometric tolerance of the flow channel is stable within ±0.01mm. This completely eliminates the stress concentration and sealing risks caused by deep hole drilling in traditional CNC machining. The 3D-printed structure avoids flow channel splicing points, ensuring the sealing and structural reliability of the refrigerant channel. Simultaneously, 3D printing allows for the free design of complex flow channels, providing manufacturing feasibility for the spiral shape and expansion structure of the heat dissipation holes 7, making the heat dissipation structure of this solution feasible for engineering applications.

[0052] The motor operates more stably in volatile scenarios such as photovoltaic manufacturing, with a lower failure rate, improved overall efficiency, reduced life-cycle costs, lower noise levels, and further reduction in size and weight. This provides a reliable, efficient, and economical heat dissipation solution for the in-depth application of variable frequency screw compressors under the "dual carbon" strategy.

[0053] The present invention also provides a screw compressor, including a motor, and the screw compressor further includes a first screw 1 and a second screw, the second screw and the first screw 1 meshing.

[0054] Integrating the aforementioned motor with a high-efficiency rotor heat dissipation structure into a screw compressor allows the rotor permanent magnets to be fully cooled during operation, thus avoiding the sudden drop in motor torque (15%-30%) and efficiency degradation caused by high-temperature demagnetization. This also prevents cascading failures such as gas supply pressure fluctuations, frequent start-stop cycles, and even electrical fires. Simultaneously, the refrigerant flow path is seamlessly integrated with the screw compressor's refrigerant circulation system, achieving synergistic optimization of rotor heat dissipation and compression refrigeration, and improving the stability of the compressor under continuous full-load operation in high-reliability scenarios such as photovoltaic manufacturing and semiconductors.

[0055] Preferred, such as Figure 1 As shown, the screw compressor also includes a support frame 9, which has a bearing hole 10 and a bearing 11 is installed in the bearing hole 10. One end of the thick shaft section 2 connected to the thin shaft section 3 passes through the bearing 11. The outlet direction of the heat dissipation hole 7 coincides with that of the bearing 11.

[0056] The outlet direction of the heat dissipation hole 7 coincides with that of the bearing 11, meaning that the high-temperature refrigerant flowing out of the heat dissipation hole 7 passes directly through the bearing 11 area. This design has a dual effect: first, the refrigerant continues to flow through the bearing 11 after exiting the heat dissipation hole 7, providing additional cooling to the bearing 11, reducing its operating temperature, and extending its lifespan; second, the bearing 11 area is a critical node for heat conduction between the rotor and the support frame 9, and the refrigerant flowing through this area can carry away the heat from this node, further blocking the path of heat conduction from the rotor to the outside, and enhancing the overall heat dissipation effect.

[0057] Preferred, such as Figure 1 As shown, the bearing 11 includes an outer ring and an inner ring, with an annular gap between the outer ring and the inner ring, and the outlet direction of the heat dissipation hole 7 is toward the annular gap.

[0058] The outlet direction of the heat dissipation hole 7 is towards the annular gap, allowing the refrigerant to directly enter the rolling element area of ​​the bearing 11 for cooling. This location is the area where the heat generation of the bearing 11 is most concentrated, and the refrigerant directly contacts the rolling elements for heat exchange, resulting in the highest cooling efficiency. At the same time, after flowing through the annular gap, the refrigerant can continue to flow axially without being blocked, thus ensuring the unobstructed flow of the heat dissipation hole 7.

[0059] Preferred, such as Figure 1 As shown, the support frame 9 is provided with a through hole that extends through the support frame 9 itself along the axial direction of the first screw 1, and there are at least two heat dissipation holes 7, with the outlet direction of some of the heat dissipation holes 7 facing the through hole.

[0060] Some of the heat dissipation holes 7 have outlets that coincide with the through holes in their axial projection, allowing the refrigerant flowing out of the heat dissipation holes 7 to be further discharged outwards or participate in external refrigerant circulation through the through holes. The through holes provide a heat dissipation path for the refrigerant from the rotor bushing 4, to the bearing 11 area, and then to the outside of the support frame 9, preventing the refrigerant from accumulating near the bearing 11 and causing a decrease in heat dissipation efficiency; multiple heat dissipation holes 7, together with the through holes, form a distributed heat dissipation outlet, improving the uniformity and reliability of overall heat dissipation.

[0061] Preferably, there are multiple through holes, which are arranged around the bearing hole 10, and the bearing 11 is interference-fitted into the bearing hole 10.

[0062] Multiple through holes are arranged around the bearing hole 10, allowing the refrigerant to flow out from the heat dissipation hole 7 and be discharged radially in multiple directions, forming a 360° surround cooling of the bearing 11. This layout avoids localized overheating caused by heat dissipation in one direction, making the temperature distribution of the bearing 11 more uniform. At the same time, the multi-through hole structure increases the effective heat dissipation area on the support frame 9, and together with the heat dissipation hole 7 of the bushing 4, a multi-level heat dissipation network is constructed from the inside of the rotor to the outside of the support frame 9, maximizing the cooling efficiency of the whole machine and providing reliable thermal management protection for the stable operation of the variable frequency screw compressor under high load fluctuation conditions. Since the bearing 11 is interference-fitted into the bearing hole 10, and the multiple through holes are arranged around the bearing hole 10, the through holes provide space for the deformation of the support frame 9 when the bearing 11 is installed, allowing the support to deform to a certain extent when cooled or heated, thereby avoiding excessive compression of the bearing 11 and ensuring the stable operation of the bearing 11. The screw compressor of this application belongs to the strategic emerging industry field and has energy-saving and environmentally friendly technical effects.

[0063] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. An electric motor applied to a screw compressor, the screw compressor comprising a first screw (1), the first screw (1) comprising a coarse shaft section (2) and a fine shaft section (3), the coarse shaft section (2) being provided with a threaded structure, characterized in that, The motor includes a rotor core (5), and a bushing (4) is fixedly installed inside the rotor core (5). The bushing (4) is used to fix the thin shaft section (3). The bushing (4) is provided with a heat dissipation hole (7) extending along the axial direction. The heat dissipation hole (7) penetrates the bushing (4). The maximum distance between the outlet of the heat dissipation hole (7) and the axis of the bushing (4) is greater than the radius of the thick shaft section (2).

2. The motor according to claim 1, characterized in that, The heat dissipation hole (7) extends in a spiral shape around the axis of the bushing (4).

3. The motor according to claim 1, characterized in that, From the inlet of the heat dissipation hole (7) to the outlet of the heat dissipation hole (7), the distance between the heat dissipation hole (7) and the bushing (4) gradually increases.

4. The motor according to claim 1, characterized in that, The motor also includes a housing, the inner wall of which is provided with an axially extending groove (8).

5. The motor according to any one of claims 1-4, characterized in that, The bushing (4) is formed by 3D printing.

6. A screw compressor, characterized in that, The screw compressor includes the motor described in claims 1-5, and further includes a first screw (1) and a second screw, wherein the second screw and the first screw (1) mesh.

7. The screw compressor according to claim 6, characterized in that, The screw compressor also includes a support frame (9), which is provided with a bearing hole (10). A bearing (11) is provided in the bearing hole (10). One end of the thick shaft section (2) connected to the thin shaft section (3) passes through the bearing (11). The outlet direction of the heat dissipation hole (7) coincides with that of the bearing (11).

8. The screw compressor according to claim 7, characterized in that, The bearing (11) includes an outer ring and an inner ring, with an annular gap between the outer ring and the inner ring, and the outlet direction of the heat dissipation hole (7) is toward the annular gap.

9. The screw compressor according to claim 7, characterized in that, The support frame (9) is provided with a through hole that extends through the support frame (9) along the axial direction of the first screw (1). There are at least two heat dissipation holes (7), and the outlet direction of some of the heat dissipation holes (7) is towards the through hole.

10. The screw compressor according to claim 9, characterized in that, There are multiple through holes, which are arranged around the bearing hole (10), and the bearing (11) is interference-fitted into the bearing hole (10).

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