A heat-dissipating permanent magnet motor

Abstract

The utility model discloses a heat dissipation type permanent magnet motor, including casing structure, stator system, rotor system and cooling oil circuit, the rotor system includes the pivot and rotor core, and the pivot is equipped with central axial through -hole and radial branch oil way, and the rotor core is by the stamping piece lamination and is formed, and the stamping piece is equipped with permanent magnet slot and the round flow guide hole of both ends and the long strip side wing flow guide hole of both sides, and the both form cooling oil circuit, and the cooling oil is pumped into through the pivot central oil circuit, and the pipeline formed through the flow guide hole directly washes permanent magnet surface, and then is recycled through the casing bottom oil collecting groove and end cap oil return channel. The utility model effectively promotes motor heat dissipation capacity and power density, prevents permanent magnet high temperature demagnetization.

Description

Technical Field

[0001] This utility model relates to the field of permanent magnet motor technology, and in particular to a heat-dissipating permanent magnet motor. Background Technology

[0002] Permanent magnet motors (PMMs) offer advantages such as high power density and high efficiency, making them widely used in electric vehicles, industrial drives, and other fields. However, the permanent magnets and windings generate significant heat during operation. Insufficient heat dissipation can lead to demagnetization of the permanent magnets and insulation aging, limiting motor performance improvements. Traditional air cooling and water cooling methods for the housing have limited effectiveness in cooling the rotor's internal components due to long thermal resistance paths. Existing oil cooling technologies often employ spraying or immersion methods, but the oil circuit design does not adequately consider direct and efficient cooling of the permanent magnet surface, resulting in uneven cooling, low efficiency, and complex structures. Therefore, a novel heat dissipation structure is needed to achieve directional cooling within the rotor, improving the motor's heat dissipation capacity and reliability. Utility Model Content

[0003] This application provides a heat-dissipating permanent magnet motor. By optimizing the internal oil circuit structure of the rotor, the cooling oil can directly scour the surface of the permanent magnet, solving the problems of insufficient heat dissipation and easy demagnetization of the permanent magnet, thereby achieving the technical effect of improving the power density and reliability of the motor.

[0004] This application provides a heat-dissipating permanent magnet motor, characterized in that it includes:

[0005] The housing structure is provided with an oil collection groove and an oil return channel;

[0006] A stator system, comprising a stator core and stator windings, wherein the stator core is fixed inside the housing and the stator windings are embedded in the stator core;

[0007] The rotor system includes a shaft and a rotor core. The shaft has an axial through hole drilled at its center as the main oil passage, and 4 to 6 branch oil passages extending radially to the internal cooling oil passages of the rotor. The rotor core is formed by stacking multiple rotor laminations. Multiple permanent magnet slots are evenly distributed around the circumference of each rotor lamination. The permanent magnet slots are used to accommodate permanent magnets. A circular guide hole is provided at one end of each permanent magnet slot near the shaft center. Elongated side guide holes are provided on both sides of each permanent magnet slot, parallel to the direction of the permanent magnet's large surface, at a distance of 0.5 to 1 mm from the edge of the slot. The circular guide holes are connected to the elongated side guide holes.

[0008] The cooling oil is connected to the central oil passage of the rotating shaft through a rotary joint, and is sprayed into the distribution pipe formed by the circular guide hole through the radial branch oil passage. Then it is diverted to the wall pipe formed by the side guide hole, directly scouring the surface of the permanent magnet. After heat exchange, the oil is finally collected by the oil collection tank and the oil return channel under the action of centrifugal force.

[0009] Preferably, the area of ​​the circular guide hole is 2 to 3.5 times the area of ​​the elongated side wing guide hole.

[0010] Preferably, the cooling oil is a synthetic ester insulating oil with 1-3% by volume boron nitride nanoparticles added, which increases the thermal conductivity by more than 20%.

[0011] Preferably, the mounting interface between all the permanent magnets and the rotor core is filled with a highly thermally conductive adhesive.

[0012] Preferably, the outer circular surface of the rotor is laser-processed to form micron-sized pits.

[0013] One technical solution provided in this application embodiment has at least the following technical effects or advantages:

[0014] 1. This utility model constructs a highly efficient cooling channel that reaches the surface of the permanent magnet by precisely designing interconnected circular guide holes and side wing guide holes in the rotor laminations. This significantly reduces the operating temperature of the permanent magnet by more than 30°C, while increasing the power density. Under the same temperature rise limit, the output power can be increased by more than 15%.

[0015] 2. This utility model adopts a nanofluid cooling oil and an integrated oil return channel for the housing end cover, which improves the system's heat dissipation efficiency and reliability. The overall structure is compact and suitable for the heat dissipation needs of high power density permanent magnet motors. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the heat-dissipating permanent magnet motor structure in Embodiment 1 of this application;

[0017] Figure 2 This is a schematic diagram of the rotor lamination opening in Embodiment 1 of this application.

[0018] 100-Stator system; 110-Stator core; 120-Three-phase winding; 200-Rotor system; 210-Shaft; 211-Main oil passage; 212-Branch oil passage; 220-Rotor core; 221-Rotor lamination; 221.1-Circular guide hole; 221.2-Elongated side guide hole; 300-Casing structure; 310-Casing; 311-Oil collection groove; 312-Oil return hole; 320-End cover. Detailed Implementation

[0019] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0020] Example 1

[0021] This application discloses a heat-dissipating permanent magnet motor, including a stator system 100, a rotor system 200, a cooling system, and a housing structure 300. The stator system 100 consists of a stator core 110 and three-phase windings 120. The stator core 110 is made of low-loss silicon steel sheets stacked together, and its inner circumference has uniformly distributed slots. The three-phase windings 120 are embedded in the slots and are connected in a star or delta configuration.

[0022] The rotor system 200 includes a shaft 210 and a rotor core 220. The shaft 210 is made of 42CrMo alloy steel and has an axial through hole drilled in its center as the main oil passage 211. It also has 4 to 6 branch oil passages 212 extending radially into the internal cooling oil passages in the rotor core. The rotor core is formed by stacking multiple rotor laminations 221. The laminations have permanent magnet slots to accommodate high-performance neodymium iron boron permanent magnets. The surface of the permanent magnets is covered with an alumina ceramic insulating and thermally conductive coating to prevent corrosion and block eddy current paths.

[0023] In the design of rotor lamination 221, a circular guide hole 221.1 is provided at one end of the permanent magnet slot near the axis of the rotating shaft 210. After lamination stacking, it forms an axial distribution cooling oil pipe. At the same time, on both sides of the permanent magnet slot, parallel to the direction of the large surface of the permanent magnet, at a distance of 0.5-1mm from the edge of the slot, an elongated side wing guide hole 221.2 is provided. After stacking, it forms an axial heat exchange pipe that is close to the surface of the permanent magnet. The circular guide hole 221.1 and the elongated side wing guide hole 221.2 are intersecting and connected, and the area of ​​the circular guide hole 221.1 is 2 to 3.5 times the area of ​​the elongated side wing guide hole 221.2.

[0024] Optionally, all permanent magnets and rotor core mounting interfaces are filled with a highly thermally conductive adhesive to reduce contact thermal resistance.

[0025] Optionally, the outer surface of the rotor can be laser-processed to form micron-sized pits to increase the heat dissipation area.

[0026] The housing structure 300 includes a housing 310 and an end cover 320. At the bottom of the inner cavity of the housing 310, an oil collection groove 311 is machined along the motor axis. Cooling oil dripping from the air gap or flowing along the inner wall of the housing 310 will eventually collect in this oil collection groove 311 under gravity. A radial oil return hole 312 is located at the end of the housing oil collection groove 311, communicating with the interior of the end cover 320. The end cover 320 has an internal channel formed by casting or machining. Its inlet is located on the mating surface between the end cover 320 and the housing 310, precisely aligned with the housing oil return hole 312. The outlet of the channel is located on the outer side of the end cover 320, used to connect to an external oil return pipeline. This structure employs a mature oil collection and diversion design, achieving reliable cooling oil recovery through gravity diversion and mechanical structure cooperation.

[0027] The cooling subsystem employs forced oil cooling circulation. The cooling oil is a synthetic ester insulating oil with 1-3% boron nitride nanoparticles added by volume, which increases its thermal conductivity by more than 20%. The oil enters the central oil circuit of the rotating shaft through a rotary joint, and is sprayed through radial branch oil channels to the distribution pipe formed by the end guide holes. It then flows to the wall-mounted pipe formed by the side guide holes to directly scour the surface of the permanent magnet. After heat exchange, the oil is thrown into the air gap under centrifugal force, and is finally collected by the oil collection tanks and return channels designed inside the bottom of the casing and the end cover, returning to the external heat exchanger to complete the closed-loop circulation.

[0028] When the motor provided in this embodiment is working, the cooling oil directly cools the permanent magnet through the internal flow channel of the rotor, effectively controlling the temperature rise of the motor and improving its operational reliability and lifespan.

[0029] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0030] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A heat-dissipating permanent magnet motor, characterized in that, include: The housing structure is provided with an oil collection groove and an oil return channel; A stator system, comprising a stator core and stator windings, wherein the stator core is fixed inside the housing and the stator windings are embedded in the stator core; The rotor system includes a shaft and a rotor core. The shaft has an axial through hole drilled at its center as the main oil passage, and 4 to 6 branch oil passages extending radially to the internal cooling oil passages of the rotor. The rotor core is formed by stacking multiple rotor laminations. Multiple permanent magnet slots are evenly distributed around the circumference of each rotor lamination. The permanent magnet slots are used to accommodate permanent magnets. A circular guide hole is provided at one end of each permanent magnet slot near the shaft center. Elongated side guide holes are provided on both sides of each permanent magnet slot, parallel to the direction of the permanent magnet's large surface, at a distance of 0.5 to 1 mm from the edge of the slot. The circular guide holes are connected to the elongated side guide holes. Cooling oil is connected to the central oil passage of the rotating shaft through a rotary joint, and is sprayed into the distribution pipe formed by the circular guide hole through the radial branch oil passage. It is then diverted to the wall pipe formed by the side guide hole, directly washes the surface of the permanent magnet, and is collected by the oil collection tank and the return oil channel.

2. A heat-dissipating permanent magnet motor as described in claim 1, characterized in that, The area of ​​the circular guide hole is 2 to 3.5 times the area of ​​the elongated side wing guide hole.

3. A heat-dissipating permanent magnet motor as described in claim 1, characterized in that, The cooling oil is a synthetic ester insulating oil with 1-3% boron nitride nanoparticles added by volume.

4. A heat-dissipating permanent magnet motor as described in claim 1, characterized in that, The mounting interfaces between all the permanent magnets and the rotor core are filled with a highly thermally conductive adhesive.

5. A heat-dissipating permanent magnet motor as described in claim 1, characterized in that, The outer circular surface of the rotor is laser-processed to form micron-sized pits.

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