Composite cooling structure of outer rotor hub direct drive motor

Abstract

The invention designs a composite cooling structure of an outer rotor hub direct drive motor, which is a composite cooling structure in which water cooling is adopted for a stator, a heat pipe is inserted into a winding and two cooling modes are combined, and belongs to the technical field of motor cooling. A composite cooling structure for an outer rotor hub direct drive motor adopts a cooling mode of combining water cooling of a water pipe and insertion of a heat pipe at a heat accumulation position, a cooling supporting structure is installed on the inner side of a stator, a cylindrical hole is formed in the cooling supporting structure to place a cooling water pipe, and the cooling water pipe is fixed through the cylindrical hole. The radial outer side of the cooling supporting structure is divided into a plurality of water pipe end covers, water pipes are installed after the water pipe end covers are taken out, the water pipe end covers are additionally installed after installation is completed, and the water inlet and the water outlet extend outwards for internal and external circulation of cooling liquid. In order to relieve the heat accumulation phenomenon of an outer rotor motor winding, a long-short arm U-shaped heat pipe is designed to be matched with a water cooling structure, a long arm is inserted into a sandwich position of a double-layer winding in a stator groove, a plurality of small holes are formed in a cooling supporting structure, a short arm is inserted into the small holes, and each heat pipe is inserted into the cooling supporting structure and does not exceed a corner of a water pipe. The adjacent heat pipes at the corners of the cooling water pipe are symmetrically arranged, and heat dissipation of the heat pipes is accelerated through cooling water.

Description

Technical Field

[0001] The present invention relates to the technical field of motor cooling, and particularly to a composite cooling structure for an outer-rotor hub direct-drive motor. Background Art

[0002] The hub direct-drive motor has high integration, few transmission components, and small occupied space, which helps the motor to develop towards miniaturization and light weight. Compared with the traditional drive system, higher requirements are imposed on the motor. The motor must have a high torque density. High torque density generates high heat. The motor is integrated in the hub and the internal space is airtight. High torque density necessarily requires a cooling system with strong heat dissipation ability to maintain the stability of the motor operation performance. Compared with air cooling, liquid cooling has higher cooling efficiency. According to different coolants, the liquid cooling system is mainly divided into two methods: water cooling and oil cooling. Water cooling realizes the indirect contact between the coolant and the cooled component through cooling pipes to take away heat; while oil cooling makes the coolant directly contact the cooled component through spraying, immersion and other methods, so as to achieve more efficient heat dissipation. Although the cooling efficiency of oil cooling is high, it usually requires sealing treatment of the stator, which will increase the air gap spacing and thus have a certain impact on the electromagnetic performance of the motor. In addition, the oil cooling system has high requirements for material selection and processing technology, increasing the complexity of design and manufacturing. Therefore, the present invention selects water cooling as the main cooling method. Different from the traditional inner-rotor motor, the rotor housing part of the outer-rotor hub direct-drive motor rotates with the rotor, and it is impossible to install a liquid cooling device with complex structure and high heat dissipation efficiency on the housing to dissipate heat for the stator like the inner-rotor motor. At the same time, due to the high loss and many heat sources in the stator part, a large amount of heat is generated, and local hot spots are easily formed. If the heat cannot be dissipated in time, it will cause the aging of the insulating material, directly affecting the operation performance of the motor. There is an urgent need to adopt a more direct and effective cooling design. Therefore, aiming at the problems of high heat generation and difficult heat dissipation existing in the hub direct-drive motor, a good heat dissipation system needs to be designed so that it can operate stably in high-torque and high-power-density occasions. Summary of the Invention

[0003] The present invention aims to solve the problems of single heat dissipation method, inability to install a water cooling structure on the housing, and low heat dissipation efficiency at the heat accumulation place of the outer-rotor hub direct-drive motor, and designs a new type of composite cooling structure.

[0004] The technical solution of the present invention is as follows: Design a composite cooling structure for a new type of outer-rotor hub direct-drive motor, including a water pipe, a heat pipe, a rotor, a stator, a rotor permanent magnet, a stator permanent magnet, a winding end, a winding, a cooling support structure, a water pipe end cover, a fixed shaft, a water inlet, and a water outlet. The armature winding is wound around the stator teeth, forming winding ends at the front and rear ends of the stator. Stator permanent magnets are installed at the stator teeth near the air gap, and a rotor is installed on the outer side of the stator radially. Alternating-pole rotor permanent magnets are embedded near the air gap on the rotor. A cooling support structure is tightly installed on the inner side of the stator radially. A cylindrical hole is opened on the cooling support structure to place an axial cooling water pipe. One water inlet and one water outlet are arranged at the end of the water pipe. At the same time, a water pipe end cover is separated on the outer side of the support structure radially, and a fixed shaft is placed on the inner side. One end of each U-shaped heat pipe is inserted into the double-layer winding sandwich in the stator slot, and one end is inserted into the bracket. The adjacent heat pipes at the bend of the cooling water pipe are symmetrically arranged.

[0005] Furthermore, the whole machine adopts a cooling method combining water cooling of the water pipe and insertion of the heat pipe. The water pipe is installed at the cooling support structure, and part of the stator winding is inserted into the heat pipe for cooling;

[0006] Furthermore, a cooling support structure is installed on the inner side of the stator radially. A cylindrical hole is opened on the support structure to place an axial cooling water pipe. The water pipe is closer to the internal area that is not easy to dissipate heat. The water inlet and the water outlet extend outwards through the fixed shaft for internal and external circulation of the coolant;

[0007] Furthermore, a plurality of water pipe end covers are separated on the outer side of the cooling support structure radially. After taking out the end covers, the water pipe is installed, and then the end covers are reinstalled after the installation. The number of water pipe end covers is the same as the number of flow channels where the water pipe is axially inserted into the cooling support structure;

[0008] Furthermore, the long arm of the U-shaped heat pipe is inserted into the sandwich of the double-layer winding in the stator slot, and it is on the midpoint connection line of the widest part in the slot. The short arm is inserted into the cooling support structure where the water pipe is installed;

[0009] Furthermore, the U-shaped heat pipe is designed with two arms of different lengths. The long arm extends through the winding end, and the short arm is inserted into the end of the cooling support structure not exceeding the bend of the water pipe;

[0010] Furthermore, small holes are opened on the cooling support structure, and each short arm of the heat pipe is inserted. The adjacent heat pipes at the bend of the cooling water pipe are symmetrically arranged, and the water pipe and the heat pipe are arranged alternately.

[0011] Furthermore, a heat pipe is inserted into each double-layer winding. The heat pipe is in close contact with the winding in the slot and the end winding, and no holes are drilled on other components of the motor body.

[0012] The technical solution of a composite cooling structure for a new type of outer-rotor hub direct-drive motor provided by the present invention has the following advantages:

[0013] 1. Insert heat pipes into the winding to establish additional cooling paths. The heat pipes transfer the heat of the winding to the cooling support structure, alleviating the heat accumulation phenomenon and improving the overall performance of the motor.

[0014] 2. An outer-rotor hub direct-drive motor cannot install a cooling device with complex structure and high heat dissipation efficiency on the casing like an inner-rotor motor, and the installation space is limited. Therefore, a cooling support structure is installed on the inner side of the stator of the motor and water pipes are inserted, making full use of the internal space of the motor and effectively cooling the stator, and highly integrating the cooling structure design.

[0015] 3. Insert one end of the heat pipe into the winding and the other end into the vicinity of the water pipe in the cooling support structure, arranging them alternately with the water pipe. The cooling water accelerates the heat export of the heat pipe, further improving the cooling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an overall schematic diagram of the composite cooling structure of an outer-rotor hub direct-drive motor;

[0017] Figure 2 It is a schematic diagram of the structure of the outer-rotor hub direct-drive motor body;

[0018] Figure 3 It is a schematic diagram of the composite cooling structure and part of the winding of the motor;

[0019] Figure 4 It is a sectional view of the composite cooling structure of an outer-rotor hub direct-drive motor;

[0020] Figure 5 It is a schematic diagram of the heat pipe and water pipe structure;

[0021] Figure 6 It is a schematic diagram of the flow of cooling water in the water pipe; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following further details the composite cooling structure of the outer-rotor hub direct-drive motor in the present invention in conjunction with the drawings and specific embodiments. The advantages and features of the present invention will be more clearly described below. However, it should be noted that the technical solution of the present invention has multiple different implementation forms and is not limited to the specific embodiments described. The drawings are only used to assist in explaining the content and purpose of the present invention. Therefore, the drawings are relatively simple and all use non-precise scales.

[0023] Please refer to Figures 1 to 5, the present invention provides a composite cooling structure for a novel outer rotor hub direct drive motor, including a water pipe (1), a heat pipe (2), a rotor (3), a stator (4), a rotor permanent magnet (5), a stator permanent magnet (6), a winding end (7), a winding (8), a cooling support structure (9), a water pipe end cover (10), a fixed shaft (11), a water inlet (12), and a water outlet (13).

[0024] The armature winding (8) is wound around the teeth of the stator (4), forming winding ends (7) at the front and rear ends of the stator (4). The stator permanent magnet (6) is installed near the air gap on the stator teeth. The rotor (3) is installed on the radial outer side of the stator (4), and the alternating pole rotor permanent magnet (5) is embedded near the air gap on the rotor (3). The cooling support structure (9) is tightly installed on the radial inner side of the stator (4). A cylindrical hole is opened on the cooling support structure (9) to place the axial cooling water pipe (1). One water inlet (12) and one water outlet (13) are provided at the end of the water pipe (1). At the same time, the water pipe end cover (10) is divided on the radial outer side of the cooling support structure (9), and the fixed shaft (11) is placed on the inner side. One end of each U-shaped heat pipe (2) is inserted into the sandwich of the double-layer winding (8) in the stator slot, and the other end is inserted into the bracket. The adjacent heat pipes (2) at the turning of the cooling water pipe (1) are symmetrically arranged.

[0025] The whole machine adopts a cooling method combining water cooling of the water pipe (1) and insertion of the heat pipe (2). Installing the water pipe (1) at the cooling support structure (9) not only makes full use of the internal space of the motor but also can dissipate heat from the stator (4) in a timely manner. The heat pipe (2) is inserted into the stator winding (8) for cooling. An additional cooling path is established through the heat pipe (2) to quickly export the heat of the winding, prevent local overheating, and make the temperature distribution of the whole motor more uniform.

[0026] The cooling support structure (9) is installed on the radial inner side of the stator (4). A cylindrical hole is opened on the support structure to place the axial cooling water pipe (1). The water pipe (1) is closer to the internal area that is not easy to dissipate heat. The water inlet (12) and the water outlet (13) extend outwards through the fixed shaft (11) for the internal and external circulation of the coolant. The cooling support structure (9) is mainly used to fix the water pipe (1). An aluminum cooling support structure (9) is selected. The aluminum cooling support structure material has high thermal conductivity, which helps to take away the heat of the heat pipe (2) in time through the flow of the coolant, accelerate the cooling speed, and solve the problem of difficult installation of the liquid cooling device for the outer rotor motor.

[0027] The water pipe end cover (10) is separated from the radially outer side of the cooling support structure (9). After taking out the end cover, the water pipe (1) is installed. After the installation is completed, the water pipe end cover (10) is installed again. The number of water pipe end covers (10) is the same as the number of flow channels in which the water pipe (1) is axially inserted into the cooling support structure (9). A water-cooled end cover (10) is configured for each axial water pipe (1) inserted into the bracket. The separated water pipe end cover (10) is for the convenience of installing the water pipe (1) to prevent the water pipe from not being inserted during the assembly stage or being blocked at the turning point.

[0028] Insert the long arm of the U-shaped heat pipe (2) into the sandwich of the double-layer winding (8) in the stator (4) slot. The heat pipe cooling does not require connecting additional cooling equipment. The heat pipe is light in weight and small in volume, and installing it in the slot will not significantly reduce the number of winding turns, thus not affecting the motor operation performance.

[0029] Insert the long arm of the U-shaped heat pipe (2) on the midpoint connection line of the widest part in the stator (4) slot, and insert the short arm into the cooling support structure (9) where the water pipe (1) is installed. The widest area of the slot is also the position with the most windings and the most difficult heat dissipation. The heat pipe cooling has extremely high cooling efficiency, can quickly dissipate heat from the winding, and cooperate with the water-cooling structure to quickly cool down the motor, solving the problems of heat accumulation and concentrated heat dissipation area faced by the new high-power density motor.

[0030] The U-shaped heat pipe (2) is designed with two arms of different lengths. The long arm extends through the winding end (7), and the short arm is inserted into the end of the cooling support structure (9) not exceeding the turning point of the water pipe (1). The condensation end of each heat pipe (2) is inserted into the cooling support structure (9) not exceeding the turning point of the water pipe (1), making full use of the remaining space after the installation of the water pipe (1) and achieving a high degree of integration in the limited space to the greatest extent.

[0031] Small holes are opened on the cooling support structure (9), and the short arm of each heat pipe (2) is inserted. The adjacent heat pipes (2) at the bent part of the cooling water pipe (1) are symmetrically arranged, and the water pipe (1) and the heat pipe (2) are alternately arranged. The heat derived from the heat pipe can be indirectly transferred to the cooling water through the cooling support structure (9), further accelerating the working efficiency of the heat pipe (2) and significantly reducing the temperature of the motor winding.

[0032] A heat pipe (2) is inserted into each double-layer winding (8) in the stator slot. The heat pipe is in close contact with the winding in the slot and the end winding (7). No holes are drilled on other components of the motor body, the processing and manufacturing process is simple, the influence on the electromagnetic performance of the motor is reduced, and high-efficiency output is maintained.

[0033] Use a fixed shaft (11) connected to the cooling support structure (9) to replace the traditional rotating shaft. The fixed shaft (11) is connected to the rotor rotating housing through one bearing on each of the left and right sides. In this way, the fixed shaft supports the stator without affecting the rotation of the rotor.

[0034] Figure 3 and Figure 6 show the way of inserting heat pipes into windings and the flow path of cooling water in water pipes in the composite cooling structure of an outer-rotor hub direct-drive motor, so as to illustrate the working mode of the present invention: For the outer-rotor motor of the present invention, a cooling support structure (9) is tightly installed on the radial inner side of its stator (4). A cylindrical hole is opened on the cooling support structure (9) to place an axial cooling water pipe (1). An inlet (12) and an outlet (13) are arranged at the end of the water pipe, making full use of the internal space of the motor to achieve a high degree of integration of the motor. The water pipe (1) is placed in an area closer to the inside that is not easy to dissipate heat, and timely takes the heat generated by the motor stator (4) out of the motor with the cooling water. Heat pipes (2) are inserted into the motor windings. The long arms of the U-shaped heat pipes are inserted into the sandwich of the double-layer windings in the stator slots, and are on the midpoint connection line of the widest point in the slots, and extend through the winding ends (7). The short arms are inserted into the small holes of the cooling support structure (9), and the ends do not exceed the turning point of the water pipe (1). The adjacent heat pipes (2) at the turning point of the cooling water pipe (1) are symmetrically arranged. By using the ultra-high thermal conductivity of the heat pipes, an additional cooling path is established for the windings, shortening the heat transfer path and solving the problems of heat accumulation in the windings and concentration of the heat dissipation area. The water pipes (1) and the heat pipes (2) are arranged alternately, so that the heat pipes not only dissipate heat through natural convection of air on the end faces, but also the cooling water can accelerate the heat dissipation efficiency of the heat pipes (2).

[0035] The working principle of the cooling structure described in the present invention is briefly described as follows: The cooling structure combines water cooling and adding an additional cooling path to take away heat, mainly using heat convection and heat conduction to transfer heat. By simulating the flow state and temperature reduction effect of the coolant through fluid mechanics, heat pipes with high thermal conductivity suitable for the working mode of the motor are selected to achieve the optimal cooling effect.

[0036] The above specific embodiments have detailed the principles and implementation manners of the present invention, but the present invention is not limited to the above specific embodiments. Those skilled in the art can make corresponding changes in the specific implementation manners within the scope of their knowledge according to the idea of the present invention.

Claims

1. A composite cooling structure for a new type of outer-rotor hub direct-drive motor, comprising a water pipe (1), a heat pipe (2), a rotor (3), a stator (4), a rotor permanent magnet (5), a stator permanent magnet (6), a winding end (7), a winding (8), a cooling support structure (9), a water pipe end cover (10), a fixed shaft (11), a water inlet (12), and a water outlet (13). It is characterized in that: The armature winding (8) is wound around the teeth of the stator (4), forming winding ends (7) at the front and rear ends of the stator (4). The stator permanent magnet (6) is installed near the air gap at the stator tooth part. The rotor (3) is installed on the radial outer side of the stator (4), and the alternating-pole rotor permanent magnet (5) is embedded near the air gap on the rotor (3). The cooling support structure (9) is closely installed on the radial inner side of the stator (4). A cylindrical hole is opened on the cooling support structure (9) to place the axial cooling water pipe (1). One water inlet (12) and one water outlet (13) are arranged at the end of the water pipe (1). At the same time, the water pipe end cover (10) is divided on the radial outer side of the cooling support structure (9), and the fixed shaft (11) is placed on the inner side. One end of each U-shaped heat pipe (2) is inserted into the sandwich of the double-layer winding (8) in the stator (4) slot, and the other end is inserted into the bracket. The adjacent heat pipes (2) at the bend of the cooling water pipe (1) are symmetrically arranged.

2. The composite cooling structure of a novel outer-rotor hub direct drive motor according to claim 1, characterized in that: The whole machine adopts a cooling method combining water cooling of the water pipe (1) and insertion of the heat pipe (2). The water pipe (1) is installed at the cooling support structure (9), and part of the stator winding (8) is inserted into the heat pipe (2) for cooling.

3. The composite cooling structure of a novel outer-rotor hub direct drive motor according to claim 1, wherein: The cooling support structure (9) is installed on the radial inner side of the stator (4). A cylindrical hole is opened on the support structure to place the axial cooling water pipe (1). The water pipe (1) is closer to the internal area that is not easy to dissipate heat. The water inlet (12) and the water outlet (13) extend outwards through the fixed shaft (11) for the internal and external circulation of the coolant.

4. The composite cooling structure of a novel outer-rotor hub direct-drive motor according to claim 1, characterized in that: The water pipe end cover (10) is divided on the radial outer side of the cooling support structure (9). After taking out the end cover, the water pipe (1) is installed. After the installation is completed, the water pipe end cover (10) is reinstalled. The number of water pipe end covers (10) is the same as the number of flow channels where the water pipe (1) axially inserts into the cooling support structure (9).

5. The composite cooling structure of a novel outer-rotor hub direct-drive motor according to claim 1, characterized in that: The long arm of the U-shaped heat pipe (2) is inserted into the sandwich of the double-layer winding (8) in the stator (4) slot, and it is on the midpoint connection line with the widest width in the slot. The short arm is inserted into the cooling support structure (9) where the water pipe (1) is installed.

6. The composite cooling structure of a novel outer-rotor hub direct drive motor according to claim 1, characterized in that: The U-shaped heat pipe (2) is designed with two arms of different lengths. The long arm extends through the winding end (7), and the short arm is inserted into the end of the cooling support structure (9) and does not exceed the bend of the water pipe (1).

7. A composite cooling structure of a novel outer-rotor hub direct-drive motor according to claim 1, characterized in that: Small holes are opened on the cooling support structure (9), and the short arm of each heat pipe (2) is inserted. The adjacent heat pipes (2) at the bend of the cooling water pipe (1) are symmetrically arranged, and the water pipe (1) and the heat pipe (2) are arranged alternately.

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