A motor cooling structure for a wheel hub gear box

Abstract

The application relates to a motor cooling structure coaxial with a wheel-side gear box, which comprises a main reduction shell, a motor water jacket, a rear end cover, an oil shower ring, an oil pump, an oil cooler, an oil pipe, a sealing ring, a low-voltage junction box cover plate, a stator and a rotor, the stator is fixedly assembled in the motor water jacket, the oil shower ring is installed at both ends of the motor water jacket, the rotor is rotationally arranged on the inner side of the stator, the motor water jacket is arranged in the main reduction shell, the outer wall of the motor water jacket is provided with a cooling cavity, the main reduction shell is provided with the inlet and outlet of a water channel, the main reduction shell is provided with an oil channel, the oil pump and the oil cooler are installed on the main reduction shell. The oil-water heat exchange of the oil cooler realizes heat transfer from the oil cooling system to the water cooling system, and the overall heat exchange efficiency is greatly improved; the spiral flow channel of the cooling cavity prolongs the residence time of the cooling liquid, and the heat exchange with the stator core is strengthened; the centrifugal force of the rotor drives the cooling oil to flow, and the heat dissipation effect of the rotor is further improved.

Description

Technical Field

[0001] This invention relates to the field of motor heat dissipation technology, and in particular to a motor cooling structure for use with a wheel-side gearbox coaxial. Background Technology

[0002] As the demands for power, torque, and speed of drive motors in new energy vehicles continue to increase, the stator windings, rotor magnets, and bearings will generate a large amount of heat during motor operation. If the motor is not cooled in time, it will directly lead to a decrease in motor efficiency and a shortened service life. In severe cases, it may cause fatal failures such as demagnetization of rotor magnets and burnout of stator windings. Therefore, an efficient cooling system has become one of the core aspects of motor design.

[0003] Current mainstream motor cooling technologies have significant limitations: 1. Insufficient cooling methods: The heat dissipation path of a pure water cooling system is mainly "winding → stator core → housing → coolant", while the heat dissipation path of other parts is mainly "rotor, bearings, etc. → air → housing → coolant". Therefore, there are heat dissipation blind spots in core components such as rotor, bearings, and winding ends. Although mainstream oil cooling structures in the industry (such as Tesla's core surface oil channels + end spray, and BorgWarner's centripetal cooling system) have optimized the local heat dissipation effect and achieved coverage of multiple components, they have problems such as short cooling paths and lack of synergy with water cooling systems. Moreover, the specific heat capacity of oil itself is relatively low, which leads to the cooling oil temperature rising too quickly, and the cooling efficiency is limited by the heat exchange capacity of the oil cooler.

[0004] 2. Conflicts in integrated installation: The water and oil channels of traditional motor cooling systems are mostly integrated with the motor housing, and the motor and main reducer are separate structures that require separate installation space. This cannot meet the compact requirements of the "main reducer-motor integration" of the wheel-side electric drive system of new energy vehicles, and limits the optimal utilization of the vehicle chassis space.

[0005] Based on the above problems, there is an urgent need for a collaborative cooling system that can achieve full coverage of the stator, rotor, and bearings, while taking into account both cooling efficiency and integrated installation requirements. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of existing motor cooling technology, such as "incomplete heat dissipation coverage, insufficient cooling efficiency, and difficulty in adapting to integrated installation", and to provide a water-cooling-oil-cooling synergistic cooling system for motor-main reducer coaxial motor.

[0007] The technical solution to the above technical problems is: a motor cooling structure for coaxial with a wheel-side gearbox, characterized in that: it includes a main reducer housing, a motor water jacket, a rear end cover, an oil spray ring, an oil pump, an oil cooler, an oil pipe, a sealing ring, a low-voltage junction box cover, a stator, and a rotor. The stator is fixedly assembled inside the motor water jacket, the oil spray ring is installed at both ends of the motor water jacket, the rotor is rotatably disposed inside the stator, the motor water jacket is disposed inside the main reducer housing, a cooling cavity is opened on the outer wall of the motor water jacket, the main reducer housing is designed with water inlet and outlet, the main reducer housing is designed with oil passage, and the oil pump and oil cooler are installed on the main reducer housing. The motor is cooled by either water or oil. Water cooling method: The coolant is introduced through the oil cooler and enters the cooling chamber of the motor water jacket through the connection port between the oil cooler and the main reducer housing, forming a closed loop of "external coolant → oil cooler → main reducer water channel → motor water jacket annular cooling chamber → coolant connector → external cooling system". Oil cooling method: The cooling oil circulation path is divided into a main circuit and a branch circuit, and the motor cooling oil forms its own circulation, specifically: Main circuit: cavity → oil pump → oil cooler → oil pipe → low-voltage junction box cover; Branch circuit 1: Low-voltage junction box cover plate → rotor → dynamic balance plate oil guide hole → stator winding end → cavity; Branch circuit 2: Low-voltage junction box cover → rotor oil injection hole → bearing → cavity; Branch circuit 3: Low-voltage junction box cover → rear end cover → main reducer housing → oil spray ring → stator → cavity.

[0008] A further technical solution of the present invention is: a guide plate is provided on the cooling chamber of the motor water jacket, and the guide plate divides the cooling chamber into a swirling flow channel.

[0009] It also includes a sealing assembly, which includes sealing grooves at both ends of the cooling chamber and sealing rings assembled in the sealing grooves. The sealing rings are made of fluororubber. The motor water jacket is provided with a guide stop at the corresponding sealing groove position for sealing and docking with related components to avoid damage to the sealing rings during assembly.

[0010] The oil cooler is a shell-and-tube heat exchanger, whose coolant channel is connected in series or parallel with the annular cooling chamber of the water cooling system, and whose oil channel is connected in series with the motor oil cooling circuit to achieve oil-water heat exchange.

[0011] The motor rotor core is connected to the shaft by a key. When the rotor rotates, it drives the cooling oil to flow in the axial heat dissipation oil channel. The two ends of the axial heat dissipation oil channel of the rotor are connected. A dynamic balance plate is provided at the end of the rotor. An oil guide hole is opened on the dynamic balance plate. The oil guide hole corresponds to the axial heat dissipation oil channel and is used to throw the cooling oil to the end of the stator winding.

[0012] If the motor and the wheel-side gearbox are coaxial, an oil seal is provided between the motor housing and the gearbox cavity. The oil seal is used to prevent the gearbox lubricating oil from mixing with the motor cooling oil.

[0013] By adopting the above technical solution, one of the motor cooling structures of the present invention, which is coaxial with the wheel-side gearbox, has the following beneficial effects: 1. No blind spot heat dissipation: The water cooling system covers the stator core, and the oil cooling system covers the rotor magnets, stator winding ends and bearings through multiple branch circuits, realizing all-round heat dissipation of key heat-generating components of the motor and effectively controlling the temperature of each component (the stator core temperature is about 100℃ after the system is turned on, and about 128℃ when pure water cooling is used. The test conditions are measured after the motor has been running under rated conditions until the motor reaches thermal equilibrium), avoiding performance degradation or failure due to local overheating.

[0014] 2. High cooling efficiency: The oil cooler realizes oil-water heat exchange, transferring the heat of the oil cooling system to the water cooling system, which greatly improves the overall heat exchange efficiency; the swirling flow channel design of the cooling chamber extends the residence time of the coolant and enhances the heat exchange with the stator core; the centrifugal force of the rotor drives the cooling oil to flow, further improving the rotor heat dissipation effect. Compared with a single cooling method, the overall heat dissipation efficiency is improved by more than 26%.

[0015] 3. Adaptable to integrated installation: The oil pump and oil cooler are integrated into the main reduction gear housing, and the motor water jacket is directly connected to the main reduction gear, realizing the integrated design of the main reduction gear, motor and cooling system. Compared with the traditional separate structure, the installation space is reduced by more than 15%, meeting the compact installation requirements of the wheel-side coaxial motor.

[0016] 4. High reliability: The combination design of the sealing ring and guide stop ensures reliable sealing of the water cooling system and prevents coolant leakage; the oil seal design between the motor and gearbox prevents oil mixing and ensures cooling and lubrication effects; each cooling circuit is independent and coordinated, resulting in low failure risk and improved motor operation reliability.

[0017] The technical features of a motor cooling structure coaxial with a wheel-side gearbox according to the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0018] Figure 1 : A schematic diagram of a cooling system for a two-in-one electric drive assembly.

[0019] Figure 2 : A schematic diagram of a cooling system for a two-in-one electric drive assembly.

[0020] Figure 3 Schematic diagram of the water jacket structure of the motor.

[0021] In the above figures, the reference numerals are explained as follows: 1-Main reducer housing, 2-Motor water jacket, 3-Rear end cover, 4-Oil spray ring, 5-Oil pump, 6-Oil cooler, 7-Oil pipe, 8-Sealing ring, 9-Low-voltage junction box cover, 10-Stator, 11-Rotor, 12-Guide plate. Detailed Implementation

[0022] A motor cooling structure for use with a gearbox coaxial with a wheel-side gearbox includes a main reducer housing 1, a motor water jacket 2, a rear end cover 3, an oil spray ring 4, an oil pump 5, an oil cooler 6, an oil pipe 7, a sealing ring 8, a low-voltage junction box cover 9, a stator 10, a rotor 11, and a motor shaft. The stator is fixedly assembled inside the motor water jacket, the oil spray ring is installed at both ends of the motor water jacket, and the rotor is rotatably mounted inside the stator. A cooling cavity is formed on the outer wall of the motor water jacket. The motor water jacket 2 is disposed inside the main reducer housing 1 and is interference-fitted with the main reducer housing 1. The rotor, stator, and motor shaft are respectively disposed in the main reducer housing 1. The stator is interference-fitted with the motor water jacket 2, and the rotor is connected to the motor shaft by an interference fit. The rear end cover is fixed to the main reducer housing 1.

[0023] The cooling chamber can be designed as an annular chamber according to the requirements of the main reducer housing. The sealing rings are respectively set at both ends of the motor water jacket. Two sealing grooves are designed at both ends of the cooling chamber for installing the sealing rings. The sealing ring 8 is set on the motor water jacket 2. The oil inlet port of the oil spray ring is located at the high position of the row pair when the oil spray ring is installed. The oil inlet port is connected to the main reducer housing. The main reducer housing is designed with water channel inlet and outlet. The main reducer housing is designed with oil channel. The oil pump and oil cooler are installed on the main reducer housing. The motor is cooled by either water or oil. Water cooling is provided by an oil cooler, which enters the cooling chamber of the motor water jacket through the connection port between the oil cooler and the main reducer. The motor water jacket cooling chamber is equipped with a coolant connector, which includes an inlet connector and an outlet connector. Both the inlet connector and the outlet connector are connected to the cooling chamber. The outer wall of the stator core is in contact with the inner wall of the motor water jacket cooling chamber for cooling and heat dissipation. Water cooling method: The coolant is introduced through the oil cooler and enters the cooling chamber of the motor water jacket through the connection port between the oil cooler and the main reducer housing. The main reducer housing is designed with water inlet and outlet channels. One end of the motor water jacket cooling chamber is equipped with a coolant connector (both the inlet and outlet connectors are connected to the annular cooling chamber), forming a closed loop of "external coolant → oil cooler → main reducer water channel → motor water jacket annular cooling chamber → coolant connector → external cooling system". The cooling oil is mainly stored in the inner cavity of the motor and the main reducer, and is circulated by the oil pump. The winding end of the stator, the cooling oil ring, and the oil thrown out by the rotor form a cooling structure. Several axial heat dissipation oil channels are opened inside the rotor core to dissipate heat from the magnets. Then, the oil is thrown to the stator end through the holes on the dynamic balance plate at both ends. Oil spray holes are opened on the rotor near the bearing position, and the oil is sprayed directly onto the bearing to lubricate and dissipate heat from the bearing. The heat on the oil is finally dissipated through the oil cooler and the coolant.

[0024] Oil cooling method: The cooling oil circulation path is divided into a main circuit and a branch circuit, and the motor cooling oil forms its own circulation, specifically: Main circuit: cavity (motor inner cavity / main reduction cavity) → oil pump → oil cooler → oil pipe → low-voltage junction box cover; Branch circuit 1: Low-voltage junction box cover plate → Rotor (axial cooling oil passage) → Dynamic balance plate oil guide hole → Stator winding end → Cavity; Branch circuit 2: Low-voltage junction box cover → rotor oil injection hole → bearing → cavity; Branch circuit 3: Low-voltage junction box cover → rear end cover → main reducer housing → oil spray ring → stator → cavity; The oil cooler is a shell-and-tube heat exchanger. Its coolant channel is connected in series or parallel with the annular cooling chamber of the water cooling system, and its oil channel is connected in series with the motor oil cooling circuit to achieve oil-water heat exchange. The cooling chamber of the motor water jacket is equipped with a guide plate. The annular cooling chamber is equipped with several axial guide plates and some radial guide plates. The guide plates divide the cooling chamber into a swirling flow channel (annular cavity). One side of the guide plate abuts against the outer wall of the motor water jacket, and the other side is fixed to the cavity wall of the motor housing.

[0025] It also includes a sealing assembly, which includes sealing grooves at both ends of the cooling chamber and sealing rings assembled in the sealing grooves. The sealing rings are made of fluororubber. The motor water jacket is provided with a guide stop at the corresponding sealing groove position for sealing and docking with related components to avoid damage to the sealing rings during assembly.

[0026] The motor rotor core is connected to the shaft by a key. When the rotor rotates, it drives the cooling oil to flow in the axial heat dissipation oil channel. The two ends of the axial heat dissipation oil channel of the rotor are connected. A dynamic balance plate is provided at the end of the rotor. An oil guide hole is opened on the dynamic balance plate. The oil guide hole corresponds to the axial heat dissipation oil channel and is used to throw the cooling oil to the end of the stator winding.

[0027] If the motor and the wheel-side gearbox are coaxial, an oil seal is provided between the motor housing and the gearbox cavity. The oil seal is used to prevent the gearbox lubricating oil from mixing with the motor cooling oil. Specific Implementation

[0028] A water-cooled and oil-cooled synergistic cooling system for a wheel-side coaxial motor includes a main reducer housing, a motor water jacket, a rear end cover, an oil spray ring, an oil pump, an oil cooler, oil pipes, sealing components, a low-voltage junction box cover, and the stator and rotor of the motor. The cooling circuit design is as follows: 1. Water cooling system loop design Coolant source and path: The coolant of the water cooling system is introduced through the oil cooler and enters the cooling chamber of the motor water jacket through the connection port between the oil cooler and the main reducer housing; the main reducer housing is designed with water channel inlet and outlet, and one end of the motor water jacket cooling chamber is equipped with a coolant connector (both the inlet and outlet connectors are connected to the annular cooling chamber), forming a closed loop of "external coolant → oil cooler → main reducer water channel → motor water jacket annular cooling chamber → coolant connector → external cooling system".

[0029] Heat dissipation principle: The outer wall of the stator core is tightly fitted with the inner wall of the motor water jacket cooling cavity. When the coolant flows in the swirling flow channel of the cooling cavity, it directly absorbs the heat generated by the stator core through heat conduction. Then, the heat is carried out of the motor through the coolant circulation, thus achieving efficient cooling of the stator core.

[0030] 2. Oil cooling system circuit design Cooling oil storage and power: Cooling oil is mainly stored in the inner cavity of the motor and the main reduction gear housing, and is circulated by an oil pump installed on the main reduction gear housing.

[0031] Oil cooling circuit path: The cooling oil circulation path is divided into a main circuit and branch circuits, specifically: Main circuit: cavity (motor inner cavity / main reduction cavity) → oil pump → oil cooler → oil pipe → low-voltage junction box cover; Branch circuit 1: Low-voltage junction box cover plate → Rotor (axial cooling oil passage) → Dynamic balance plate oil guide hole → Stator winding end → Cavity; Branch circuit 2: Low-voltage junction box cover → rotor oil injection hole → bearing → cavity; Branch circuit 3: Low-voltage junction box cover → rear end cover → main reducer housing → oil spray ring → stator → cavity; Multi-component heat dissipation coverage: The rotor magnets, stator winding ends, and bearings are cooled in all directions through branch circuits. At the same time, the cooling oil exchanges heat with the water cooling system when it flows through the oil cooler, thus reducing its own temperature.

[0032] 3. Component pretreatment Machining the motor water jacket: Cast according to the design dimensions and machine the relevant dimensions to make the inner wall of the water jacket fit the outer wall of the stator core; machine sealing grooves at both ends of the cooling cavity and machine guide stops.

[0033] Machining the rotor: Machining axial cooling oil channels on the rotor core as required (evenly distributed along the circumference); installing dynamic balance plates at the ends of the rotor core and machining oil guide holes on the dynamic balance plates; drilling oil injection holes (3mm diameter, 4 holes, evenly distributed along the circumference) on the rotor shaft near the bearing position.

[0034] Prepare seals and heat exchangers: Select nitrile sealing rings to match the motor water jacket sealing groove; select shell and tube heat exchangers for the oil cooler (heat exchange area 1.2㎡, coolant channel diameter 20mm, oil channel diameter 15mm).

[0035] 4. System Assembly Water cooling system assembly: Press the stator core onto the motor water jacket, ensuring that the outer wall of the stator core fits tightly against the inner wall of the motor water jacket cooling cavity; embed the sealing ring into the sealing grooves at both ends of the motor water jacket; press the motor water jacket into the main reducer housing.

[0036] Oil cooling system assembly: Fix the oil pump to the oil pump mounting base on the main reducer housing with 3 M8 bolts; fix the oil cooler to the oil cooler mounting surface on the main reducer housing with 5 M6 bolts; connect the oil cooler outlet and the low-voltage junction box cover with an oil pipe (made of oil-resistant rubber, inner diameter 12mm); install an oil seal and other sealing covers between the motor housing and the gear cavity to seal the main reducer oil chamber.

[0037] Motor component assembly: Install the rotor onto the shaft via a key connection, aligning the oil guide hole of the dynamic balance plate at the rotor end with the axial cooling oil passage; install the rear end cover and the low-pressure junction box cover, ensuring that the oil pipe and the oil passage of the low-pressure junction box cover are properly connected and sealed.

[0038] 5. System debugging and operation Load test: The motor and main reducer were installed on the bridge and on the test equipment. The motor was started to run at the rated power (210kW). The temperature of each component was monitored: the stator core temperature was stable at 100℃, and the coolant temperature rose from 65℃ to 68℃, which met the design requirements.

Claims

1. A motor cooling structure coaxial with a wheel-side gearbox, characterized in that: The system includes a main reducer housing, a motor water jacket, a rear end cover, an oil spray ring, an oil pump, an oil cooler, oil pipes, a sealing ring, a low-voltage junction box cover, a stator, and a rotor. The stator is fixedly assembled inside the motor water jacket, the oil spray ring is installed at both ends of the motor water jacket, and the rotor is rotatably mounted inside the stator. The motor water jacket is located inside the main reducer housing, and a cooling cavity is opened on the outer wall of the motor water jacket. The main reducer housing is designed with water inlet and outlet channels and oil passages. The oil pump and oil cooler are installed on the main reducer housing. The motor is cooled by either water or oil. Water cooling method: The coolant is introduced through the oil cooler and enters the cooling chamber of the motor water jacket through the connection port between the oil cooler and the main reducer housing, forming a closed loop of "external coolant → oil cooler → main reducer water channel → motor water jacket annular cooling chamber → coolant connector → external cooling system". Oil cooling method: The cooling oil circulation path is divided into a main circuit and a branch circuit. The motor cooling oil forms its own circulation loop, specifically: Main circuit: cavity → oil pump → oil cooler → oil pipe → low-voltage junction box cover; Branch circuit 1: Low-voltage junction box cover → Rotor → Dynamic balance plate oil guide hole → Stator winding end → Cavity; Branch circuit 2: Low-voltage junction box cover → rotor oil injection hole → bearing → cavity; Branch circuit 3: Low-voltage junction box cover → rear end cover → main reducer housing → oil spray ring → stator → cavity.

2. The motor cooling structure for coaxial use with a wheel-side gearbox according to claim 1, characterized in that: The cooling chamber of the motor water jacket is equipped with a guide plate, which divides the cooling chamber into a swirling flow channel.

3. A motor cooling structure for coaxial use with a wheel-side gearbox according to claim 1, characterized in that: It also includes a sealing assembly, which includes sealing grooves at both ends of the cooling chamber and sealing rings assembled in the sealing grooves. The sealing rings are made of fluororubber. The motor water jacket is provided with a guide stop at the corresponding sealing groove position for sealing and docking with related components to avoid damage to the sealing rings during assembly.

4. A motor cooling structure for coaxial use with a wheel-side gearbox according to claim 1, characterized in that: The oil cooler is a shell-and-tube heat exchanger, whose coolant channel is connected in series or parallel with the annular cooling chamber of the water cooling system, and whose oil channel is connected in series with the motor oil cooling circuit to achieve oil-water heat exchange.

5. A motor cooling structure for coaxial use with a wheel-side gearbox according to claim 1, characterized in that: The motor rotor core is connected to the shaft by a key. When the rotor rotates, it drives the cooling oil to flow in the axial heat dissipation oil channel. The two ends of the axial heat dissipation oil channel of the rotor are connected. A dynamic balance plate is provided at the end of the rotor. An oil guide hole is opened on the dynamic balance plate. The oil guide hole corresponds to the axial heat dissipation oil channel and is used to throw the cooling oil to the end of the stator winding.

6. A motor cooling structure coaxial with a wheel-side gearbox according to claim 1, characterized in that: If the motor and the wheel-side gearbox are coaxial, an oil seal is provided between the motor housing and the gearbox cavity. The oil seal is used to prevent the gearbox lubricating oil from mixing with the motor cooling oil.

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