An oil-cooled electric drive system and a cooling oil circuit system for an oil-cooled electric drive system

Abstract

The application discloses an oil-cooled electric drive system and a cooling oil circuit system for the oil-cooled electric drive system, which comprises a motor stator, a motor rotor, a reducer shaft, a motor bearing, a conductive brush, a three-phase wiring seat, a reducer front bearing, a reducer rear bearing, a motor rear end cover and a shell. The oil circuit integrated scheme is simple and convenient, and can realize efficient lubrication of the motor stator, the rotor, the bearing and the shaft tooth. The combination scheme of the three-phase filter, the conductive brush and the conductive oil seal is adopted to inhibit the generation of the shaft current, effectively lead the shaft current to the ground, solve the bearing electric corrosion problem and improve the rotating system life. The integrated scheme of the reducer common cavity and the common bearing scheme improves the electric drive integration. The plug-in connector, the magnetic ring, the bus bar and the sealing structure are adopted to realize the high integration of the motor and the inverter, reduce the volume and improve the assembly convenience and the sealing reliability. The temperature sensor and the bus bar are integrated and arranged, and the problem that the temperature sensor is splashed by oil and the hot spot collection is inaccurate is avoided.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to an oil-cooled electric drive system and a cooling oil circuit system for the oil-cooled electric drive system. Background Technology

[0002] Currently, passenger vehicle electric drive systems generally suffer from the following problems and challenges: 1. Most systems use water cooling, which results in poor heat dissipation and low continuous power. A few products use oil cooling, but this cannot accurately cool heat-generating components, leading to uneven heat dissipation and poor overall cooling performance. 2. Bearings lack protective measures, resulting in severe bearing electro-corrosion, which affects bearing lifespan and the NVH performance of the electric drive. 3. The integration and modularization of components are not high, assembly is complex, the electric drive system is large in size, and the power density is low. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes an oil-cooled electric drive system with a simple integrated oil circuit design, enabling efficient lubrication of the motor stator, rotor, bearings, and shaft gears. By employing a combination of a three-phase filter, conductive brushes, and conductive oil seals, the system suppresses shaft current generation and effectively guides it to ground, addressing bearing electro-corrosion issues and extending the lifespan of the rotating system. The integrated design utilizes a shared reducer cavity and shared bearings to enhance the overall integration of the electric drive system. The integrated design of connectors, magnetic rings, busbars, and sealing structures achieves a high degree of integration between the motor and inverter, reducing size and improving assembly convenience and sealing reliability. The integrated arrangement of the temperature sensor and busbar avoids the problem of inaccurate temperature readings due to oil splashing onto the sensor's hotspots.

[0004] The present invention provides an oil-cooled electric drive system, comprising a motor stator, a motor rotor, a reducer shaft, a motor bearing, conductive brushes, a three-phase terminal block, a front bearing of the reducer, a rear bearing of the reducer, a rear end cover of the motor, and a housing.

[0005] The motor stator is fixed inside the housing, and the motor rotor is sleeved inside the motor stator. The front end of the motor shaft of the motor rotor is fitted with the inner diameter of the rear end of the reducer shaft through a clearance fit. The motor bearing is rotatably sleeved on the rear end of the motor shaft of the motor rotor and is fixedly fitted inside the housing. The rear end cover of the motor is fastened to the rear end of the housing and is coaxial with the motor shaft. The conductive brush is slidably sleeved on the rear end of the motor shaft, and the outer edge of the conductive brush is embedded and fixed on the rear end cover of the motor. The three-phase terminal block is set on the housing and is electrically connected to the motor stator through wires. The front and rear bearings of the reducer are respectively sleeved on the front and rear ends of the reducer shaft and are fixed inside the housing. Typically, one... The shaft requires two bearings for support, one at the front and one at the rear. This solution employs a three-bearing configuration. The rear bearing of the reducer is fitted onto the reducer shaft, supporting both the rear end of the reducer shaft and the front end of the motor shaft. The front end of the motor shaft is fitted with the inner diameter of the rear end of the reducer shaft using a clearance fit, ensuring support and assembly stability. This clearance fit avoids stress caused by forced assembly due to misalignment caused by tolerances in the motor and reducer, thus extending the shaft's lifespan. The three-bearing support scheme saves one bearing, reducing costs. It also saves space in the housing used to support the bearings, reducing housing weight and contributing to lightweight design and lower costs.

[0006] The conductive brush is formed by connecting and fixing an annular conductive material and a conductive metal ring by pressing. The inner end of the annular conductive material slides in contact with the rear side wall of the motor shaft, and the outer ring of the conductive metal ring is embedded and fixed on the rear end cover of the motor. A conductive circuit is formed through frictional contact between the conductive material and the motor shaft.

[0007] The conductive material is made of conductive fiber or conductive plastic. Generally, conductive fibers have good contact with the motor shaft, and finer conductive fibers can reduce the skin effect and have strong conductivity.

[0008] The conductive fiber material has a conductive coating on its surface. The conductivity of the conductive fiber is improved by adding a conductive coating. At the same time, adding a coating can increase the hardness of the conductive fiber, improve its ability to break the oil film formed on the motor shaft surface, and prevent oil corrosion by adding a coating to the surface of the conductive fiber. The conductivity of the conductive brush in an oil environment can be greatly improved without the need for an oil seal, thus eliminating the need for an oil seal and reducing costs.

[0009] The conductive fiber material has a transition fit between the inner ring end and the motor shaft. If the conductive fiber is too long, although the contact effect with the motor shaft is good, it is not conducive to removing the oil film formed on the surface of the motor shaft. Shortening the length of the conductive fiber can improve the ability of the conductive fiber to break the oil film formed on the shaft surface and improve the conductivity of the conductive brush in the oil environment.

[0010] The present invention provides an oil-cooled electric drive system, which further includes a conductive oil seal. The outer edge of the conductive oil seal is embedded and fixed on the rear end cover of the motor, and the conductive oil seal is slidably sleeved on the motor shaft between the conductive brush and the motor bearing. The conductive brush and the conductive oil seal are adjacent to each other. The rear end cover of the motor and the conductive oil seal form an independent cavity. The conductive oil seal isolates the cooling oil in the electric drive system, allowing the conductive parts of the conductive brush and the conductive oil seal to work in an oil-free environment, thereby improving conductivity. When the conductive brush forms an oil film on the shaft in an oily environment, it increases resistance or even blocks the conduction of electricity, affecting conductivity. In addition, the conductive material will absorb oil or deteriorate due to long-term operation in an oily environment, resulting in a decrease in its conductivity.

[0011] The conductive oil seal consists of an oil seal body and a conductive non-woven fabric adhered to the end face of the oil seal body, so as to perform the function of sealing oil and conducting electricity.

[0012] The conductive brush and the conductive oil seal are in contact with each other and are bonded together. The conductive brush and the conductive oil seal are integrated into a single component by bonding, which has the functions of conducting electricity and sealing oil, while also reducing the axial space occupied.

[0013] If the motor shaft lacks conductive brushes or conductive oil seals, voltage buildup in the bearing can cause the oil seal to break down, resulting in a discharge phenomenon. Prolonged discharge can damage the bearing raceway, increasing friction and leading to reduced bearing life and increased system noise. Figure 7 As shown, the influence of having conductive brushes or conductive oil seals on the motor shaft can be compared from the shaft current conduction path diagram. When the current enters the stator through the filter magnetic ring, the filter magnetic ring will filter out part of the high-frequency voltage and suppress the generation of shaft current, but shaft current will still be generated. When there are no conductive brushes or conductive oil seals, part A is the shaft current breaking through the bearing oil film and conducting to ground, which will electro-corrode the bearing. When there is a conductive oil seal, part B is the conduction to ground through the conductive oil seal. When there are conductive brushes, part C is the conduction to ground through the conductive brushes.

[0014] The oil-cooled electric drive system of the present invention also includes a vent valve, which is located in the middle of the rear end cover of the motor. Since the rear end cover of the motor and the conductive oil seal form an independent cavity, the thermal expansion of the cavity in the high temperature environment will cause the oil seal to leak oil. Therefore, a vent valve is added in order to balance the air pressure, so as to play a role in waterproofing and ventilating, and to balance the internal and external pressure difference.

[0015] The three-phase terminal block includes an integrated 4-pin connector and an 8-pin connector. The motor side of the terminal block has both 4-pin and 8-pin connectors. The 8-pin connector is used for the resolver signal line, and the 4-pin connector is used for the motor stator temperature signal line. The two connectors are integrated together, saving space. The mating 4-pin and 8-pin connectors can be assembled and disassembled via keyways on opposite sides. They can be assembled and inserted into the low-voltage signal port on the motor side of the three-phase terminal block. This connection scheme saves space and decouples the resolver and temperature signals before assembly, allowing them to reside on different components. The inverter side of the three-phase terminal block integrates high-voltage three-phase copper busbars (U-phase, V-phase, and t-phase), a fourth-phase copper busbar, and a filter magnetic ring. The three-phase terminal block connects the inverter and motor three-phase currents. The fourth-phase copper busbar is used for reverse charging of the battery by the motor, and the filter magnetic ring filters the three-phase current, suppressing shaft current generation and improving bearing electro-corrosion.

[0016] The 7-motor stator includes a stator core, a high-voltage copper busbar, a busbar assembly, and a stator temperature sensor. The high-voltage copper busbar passes through the stator core, and the busbar assembly is connected to the upper end of the high-voltage copper busbar. A square groove is provided on the busbar assembly, and the square-headed stator temperature sensor is housed in the square groove on the busbar assembly and fixed by potting glue. The stator temperature sensor is close to the high-voltage copper busbar, which can better approach the hot spot. This assembly method fixes the temperature sensor inside the busbar, which is not easily affected by the cooling oil of the oil-cooled motor, and can measure the high temperature point of the stator more closely.

[0017] This invention also provides a cooling oil circuit system for an oil-cooled electric drive system. The motor and reducer housings are connected to a coarse filter via an oil circuit. The coarse filter is connected to the inlet of an electric pump via an oil circuit, and the outlet of the electric pump is connected to a fine filter via an oil circuit. The upstream ends of the parallel reducer bearing oil circuit branch and the differential gear oil circuit branch are both connected to the electric pump outlet. The fine filter is connected to a radiator via an oil circuit. The upstream ends of the parallel motor stator oil circuit branch, motor rotor oil circuit branch, motor bearing and reducer front and rear bearing oil circuit branches, and reducer first-stage gear oil circuit branch are all connected to the radiator. The downstream ends of the reducer bearing oil circuit branch, differential gear oil circuit branch, motor stator oil circuit branch, motor rotor oil circuit branch, motor bearing and reducer front and rear bearing oil circuit branches, and reducer first-stage gear oil circuit branch are all connected to... The motor and reducer housing: The oil in the motor and reducer housing is filtered through a coarse filter to remove large particles. Then, it is pressurized by an electric pump, forming two oil paths. One path is pumped to a fine filter to remove tiny particles, ensuring that the oil entering the motor meets the motor's requirements and preventing debris from damaging the insulation system and causing insulation failure due to agitation by the motor rotor. After being cooled by a radiator, the oil then flows through the reducer housing oil circuit to the motor stator, motor rotor, motor bearings, and the front and rear bearings and first-stage gear of the reducer. The other path of oil bypasses the fine filter and is directly pumped to the reducer bearings and differential gears. This oil circuit arrangement allows for adjustment of the diameter of each branch oil circuit on the housing to meet the cooling flow requirements of each component, making the oil circuit simple and reliable.

[0018] Beneficial effects

[0019] This invention presents a simple integrated oil circuit design that enables efficient lubrication of the motor stator, rotor, bearings, and shaft gears. By employing a combination of a three-phase filter, conductive brushes, and conductive oil seals, it suppresses shaft current generation and effectively guides it to ground, addressing bearing electro-corrosion issues through multiple measures and extending the lifespan of the rotating system. The integrated design utilizes a shared cavity for the reducer and a shared bearing design to enhance the integration of the electric drive. The integrated design of connectors, magnetic rings, busbars, and sealing structures achieves a high degree of integration between the motor and inverter, reducing size and improving assembly convenience and sealing reliability. The integrated arrangement of the temperature sensor and busbar avoids the problem of inaccurate temperature readings due to oil splashing onto the sensor's hotspot. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the cooling oil circuit system of the present invention.

[0021] Figure 2 This is a schematic diagram of the electric drive system structure of the present invention. Figure 1 .

[0022] Figure 3 This is a schematic diagram of the electric drive system structure of the present invention. Figure 1 .

[0023] Figure 4 This is a schematic diagram of the internal structure of the electric drive system of the present invention.

[0024] Figure 5 This is a schematic diagram of the conductive oil seal structure of the present invention.

[0025] Figure 6 This is a schematic diagram of the conductive brush structure of the present invention.

[0026] Figure 7 This is a schematic diagram of the shaft current conduction path of the present invention.

[0027] Figure 8 This is a schematic diagram of the three-phase terminal block structure of the present invention.

[0028] Figure 9 This is a schematic diagram of the motor stator structure of the present invention.

[0029] Figure 10 This is a schematic diagram of the temperature sensor of the present invention.

[0030] Figure 11 This is a schematic diagram of the busbar structure of the present invention.

[0031] In the picture:

[0032] 1. Electric motor;

[0033] 1.1 Motor stator;

[0034] 1.1.1 Stator core;

[0035] 1.1.2 High-voltage copper busbar;

[0036] 1.1.3 Busbar Assembly;

[0037] 1.1.3.1, Square groove;

[0038] 1.1.4 Stator temperature sensor;

[0039] 1.2 Motor rotor;

[0040] 1.2.1 Motor shaft;

[0041] 1.3, Reducer shaft;

[0042] 1.4 Motor bearings;

[0043] 1.5 Conductive brush;

[0044] 1.5.1 Conductive materials;

[0045] 1.5.2 Conductive metal ring;

[0046] 1.6 Three-phase terminal block;

[0047] 1.6.1, 4-pin connector;

[0048] 1.6.2, 8-pin connector;

[0049] 1.6.3, U-phase copper busbar;

[0050] 1.6.4, V-phase copper busbar;

[0051] 1.6.5, V-phase copper busbar;

[0052] 1.6.6, Fourth Phase Copper Busbar;

[0053] 1.6.7 Filter magnetic ring;

[0054] 1.7. Front bearing of the reducer;

[0055] 1.8. Rear bearing of the reducer;

[0056] 1.9 Motor rear end cover;

[0057] 1.10, Casing;

[0058] 1.11. Conductive oil seal;

[0059] 1.11.1 Oil seal body;

[0060] 1.11.2 Conductive nonwoven fabric;

[0061] 1.12. Vent valve;

[0062] 2. 4-pin connector;

[0063] 3. 8-pin connector;

[0064] 4. Speed ​​reducer;

[0065] 4.1 Reducer bearings;

[0066] 4.2, First stage gear of the reducer;

[0067] 5. Coarse filtration;

[0068] 6. Electric pump;

[0069] 7. Fine filtration;

[0070] 8. Radiator;

[0071] 9. Differential gear;

[0072] 10. Motor and reducer housing;

[0073] A. The shaft current breaks down the bearing oil film and then conducts to ground;

[0074] B. Grounding is achieved through a conductive oil seal;

[0075] C. Grounding is achieved through a conductive brush. Detailed Implementation

[0076] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0077] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0078] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0079] Example 1

[0080] See Figures 2-11 As shown, an oil-cooled electric drive system includes a motor stator 1.1, a motor rotor 1.2, a reducer shaft 1.3, a motor bearing 1.4, a conductive brush 1.5, a three-phase terminal block 1.6, a reducer front bearing 1.7, a reducer rear bearing 1.8, a motor rear end cover 1.9, and a housing 1.10.

[0081] The motor stator 1.1 is fixed inside the housing 1.10, and the motor rotor 1.2 is sleeved inside the motor stator 1.1. The front end of the motor shaft 1.2.1 of the motor rotor 1.2 is clearance-fitted with the inner diameter of the rear end of the reducer shaft 1.3 through its outer diameter. The motor bearing 1.4 is rotatably sleeved on the rear end of the motor shaft 1.2.1 of the motor rotor 1.2. The motor bearing 1.4 is matched and fixed inside the housing 1.10. The rear end cover 1.9 of the motor is fastened to the rear end of the housing 1.10, and the rear end cover 1.9 of the motor is also attached to the motor shaft 1. 2.1 Coaxial, conductive brush 1.5 is slidably sleeved on the rear end of motor shaft 1.2.1, and the outer edge of conductive brush 1.5 is embedded and fixed on the rear end cover 1.9 of motor. Three-phase terminal block 1.6 is set on housing 1.10, and three-phase terminal block 1.6 is electrically connected to motor stator 1.1 through wires. Reducer front bearing 1.7 and reducer rear bearing 1.8 are respectively sleeved on the front and rear ends of reducer shaft 1.3, and reducer front bearing 1.7 and reducer rear bearing 1.8 are respectively fixed in housing 1.10.

[0082] See Figure 6 As shown, the conductive brush 1.5 is connected and fixed by a ring-shaped conductive material 1.5.1 and a conductive metal ring 1.5.2 through a pressing method. The inner end of the ring-shaped conductive material 1.5.1 slides in contact with the rear end side wall of the motor shaft 1.2.1, and the outer ring of the conductive metal ring 1.5.2 is embedded and fixed on the rear end cover 1.9 of the motor.

[0083] The conductive material 1.5.1 is made of conductive fiber.

[0084] The conductive fiber material 1.5.1 has a conductive coating on its surface.

[0085] The conductive fiber material 1.5.1 has a transition fit between its inner ring end and the motor shaft 1.2.1.

[0086] An oil-cooled electric drive system further includes a conductive oil seal 1.11, the outer edge of which is embedded and fixed on the rear end cover 1.9 of the motor, and the conductive oil seal 1.11 is slidably sleeved on the motor shaft 1.2.1 between the conductive brush 1.5 and the motor bearing 1.4, wherein the conductive brush 1.5 and the conductive oil seal 1.11 are adjacent to each other.

[0087] See Figure 5 As shown, the conductive oil seal 1.11 is composed of an oil seal body 1.11.1 and a conductive non-woven fabric 1.11.2 adhered to the end face of the oil seal body 1.11.1.

[0088] The conductive brush 1.5 and the conductive oil seal 1.11 are in contact with each other and are bonded and fixed.

[0089] If the motor shaft lacks conductive brushes or conductive oil seals, voltage buildup in the bearing can cause the oil seal to break down, resulting in a discharge phenomenon. Prolonged discharge can damage the bearing raceway, increasing friction and leading to reduced bearing life and increased system noise. Figure 7 As shown, the influence of having conductive brushes or conductive oil seals on the motor shaft can be compared from the shaft current conduction path diagram. When the current enters the stator through the filter magnetic ring 1.6.7, the filter magnetic ring 1.6.7 will filter out some high-frequency voltage and suppress the generation of shaft current, but shaft current will still be generated. When there are no conductive brushes or conductive oil seals, part A is the shaft current breaking through the bearing oil film and conducting to ground, which will electro-corrode the bearing. When there is a conductive oil seal, part B is the conduction to ground through the conductive oil seal. When there are conductive brushes, part C is the conduction to ground through the conductive brushes.

[0090] An oil-cooled electric drive system further includes a vent valve 1.12, which is disposed in the middle of the rear end cover 1.9 of the motor.

[0091] See Figure 8 As shown, the three-phase terminal block 1.6 includes an integrally formed 4-pin connector and an 8-pin connector. The motor side of the three-phase terminal block 1.6 is provided with a 4-pin wiring hole 1.6.1 and an 8-pin wiring hole 1.6.2. The mating ends of the 4-pin connector 2 and the 8-pin connector 3 can be assembled and disassembled by the keyway on the opposite side. The inverter side of the three-phase terminal block 1.6 integrates a high-voltage three-phase connecting copper busbar, namely the U-phase copper busbar 1.6.3, the V-phase copper busbar 1.6.4, and the V-phase copper busbar 1.6.5, and also integrates a fourth-phase copper busbar 1.6.6 and a filter magnetic ring 1.6.7.

[0092] See Figures 9-11 As shown, the motor stator 1.1 includes a stator core 1.1.1, a high-voltage copper busbar 1.1.2, a busbar assembly 1.1.3, and a stator temperature sensor 1.1.4. The high-voltage copper busbar 1.1.2 passes through the stator core 1.1.1. The busbar assembly 1.1.3 is connected to the upper end of the high-voltage copper busbar 1.1.2. A square groove 1.1.3.1 is provided on the busbar assembly 1.1.3. The square-headed stator temperature sensor 1.1.4 is housed in the square groove 1.1.3.1 on the busbar assembly 1.1.3 and is fixed by potting glue. The stator temperature sensor 1.1.4 is adjacent to the high-voltage copper busbar above.

[0093] Example 2

[0094] See Figures 1-4As shown, a cooling oil circuit system for an oil-cooled electric drive system includes a motor 1 and a reducer 4 cavity 10 connected to a coarse filter 5 via an oil circuit. The coarse filter 5 is connected to the inlet of an electric pump 6 via an oil circuit, and the outlet of the electric pump 6 is connected to a fine filter 7 via an oil circuit. The upstream ends of the oil circuit branches of the reducer bearing 4.1 and the differential gear 9, which are connected in parallel, are both connected to the outlet of the electric pump 6. The fine filter 7 is connected to a radiator 8 via an oil circuit. The motor stator 1.1 and the motor rotor 1.2 oil circuit branches are also connected in parallel. The upstream ends of the motor bearing 1.4, the front and rear bearings 1.7 and 1.8 of the reducer, and the oil circuit branch of the first-stage gear 4.2 of the reducer are all connected to the radiator 8; the downstream ends of the reducer bearing 4.1 oil circuit branch, the differential gear 9 oil circuit branch, the motor stator 1.1 oil circuit branch, the motor rotor 1.2 oil circuit branch, the motor bearing 1.4, the front and rear bearings 1.7 and 1.8 of the reducer, and the oil circuit branch of the first-stage gear 4.2 of the reducer are all connected to the cavity of the motor 1 and the reducer 4.

[0095] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. An oil-cooled electric drive system, characterized in that: Includes motor stator (1.1), motor rotor (1.2), reducer shaft (1.3), motor bearing (1.4), conductive brush (1.5), three-phase terminal block (1.6), reducer front bearing (1.7), reducer rear bearing (1.8), motor rear end cover (1.9), and housing (1.10). The motor stator (1.1) is fixed inside the housing (1.10), and the motor rotor (1.2) is sleeved inside the motor stator (1.1). The front end of the motor shaft (1.2.1) of the motor rotor (1.2) is fitted with the inner diameter of the rear end of the reducer shaft (1.3) through a clearance fit. The motor bearing (1.4) is rotatably sleeved on the rear end of the motor shaft (1.2.1) of the motor rotor (1.2). The motor bearing (1.4) is matched and fixed inside the housing (1.10). The rear end cover (1.9) of the motor is fastened to the rear end of the housing (1.10), and the rear end cover (1.9) and the motor shaft (1.10) are aligned. 2.1) Coaxial, the conductive brush (1.5) is slidably sleeved on the rear end of the motor shaft (1.2.1), and the outer edge of the conductive brush (1.5) is embedded and fixed on the rear end cover (1.9) of the motor. The three-phase terminal block (1.6) is set on the housing (1.10), and the three-phase terminal block (1.6) is electrically connected to the motor stator (1.1) through the wire. The front bearing (1.7) and the rear bearing (1.8) of the reducer are respectively sleeved on the front and rear ends of the reducer shaft (1.3), and the front bearing (1.7) and the rear bearing (1.8) of the reducer are respectively fixed in the housing (1.10); The motor (1) and reducer (4) cavity (10) are connected to the coarse filter (5) via an oil circuit. The coarse filter (5) is connected to the inlet of the electric pump (6) via an oil circuit. The outlet of the electric pump (6) is connected to the fine filter (7) via an oil circuit. The upstream ends of the oil circuit branches of the reducer bearing (4.1) and the differential gear (9) are connected to the outlet of the electric pump (6). The fine filter (7) is connected to the radiator (8) via an oil circuit. The motor stator (1.1) oil circuit branch, the motor rotor (1.2) oil circuit branch, and the motor bearing (1.4) are connected to each other in parallel. The upstream ends of the oil circuit branches of the front and rear bearings (1.7) and (1.8) of the reducer and the oil circuit branch of the first gear (4.2) of the reducer are all connected to the radiator (8); the oil circuit branches of the reducer bearing (4.1), the oil circuit branch of the differential gear (9), the oil circuit branch of the motor stator (1.1), the oil circuit branch of the motor rotor (1.2), the oil circuit branch of the motor bearing (1.4), and the downstream ends of the oil circuit branches of the front and rear bearings (1.7) and (1.8) of the reducer and the oil circuit branch of the first gear (4.2) of the reducer are all connected to the motor (1) and the reducer (4) cavity.

2. The oil-cooled electric drive system according to claim 1, characterized in that: The conductive brush (1.5) is connected and fixed by a ring-shaped conductive material (1.5.1) and a conductive metal ring (1.5.2) through a pressing method. The inner end of the ring-shaped conductive material (1.5.1) slides in contact with the rear side wall of the motor shaft (1.2.1), and the outer ring of the conductive metal ring (1.5.2) is embedded and fixed on the rear end cover (1.9) of the motor. The conductive material (1.5.1) is made of conductive fiber or conductive plastic.

3. The oil-cooled electric drive system according to claim 2, characterized in that: The conductive material (1.5.1) made of conductive fiber is covered with a conductive coating; the inner ring end of the conductive material (1.5.1) made of conductive fiber is in transition fit with the motor shaft (1.2.1).

4. The oil-cooled electric drive system according to claim 1, characterized in that: It also includes a conductive oil seal (1.11), the outer edge of which is embedded and fixed on the rear end cover (1.9) of the motor, and the conductive oil seal (1.11) is matched and slidably sleeved on the motor shaft (1.2.1) between the conductive brush (1.5) and the motor bearing (1.4), wherein the conductive brush (1.5) and the conductive oil seal (1.11) are adjacent to each other.

5. The oil-cooled electric drive system according to claim 4, characterized in that: The conductive oil seal (1.11) consists of an oil seal body (1.11.1) and a conductive non-woven fabric (1.11.2) adhered to the end face of the oil seal body (1.11.1).

6. The oil-cooled electric drive system according to claim 5, characterized in that: The conductive brush (1.5) and the conductive oil seal (1.11) are in contact with each other and are bonded and fixed.

7. The oil-cooled electric drive system according to claim 1, characterized in that: It also includes a vent valve (1.12), which is located in the middle of the rear end cover (1.9) of the motor.

8. The oil-cooled electric drive system according to claim 1, characterized in that: The three-phase terminal block (1.6) includes an integrally formed 4-pin connector and an 8-pin connector. The motor side of the three-phase terminal block (1.6) is provided with a 4-pin wiring hole (1.6.1) and an 8-pin wiring hole (1.6.2). The 4-pin connector (2) and the 8-pin connector (3) at the mating end can be assembled and disassembled by the keyway on the opposite side. The inverter side of the three-phase terminal block (1.6) integrates a high-voltage three-phase connecting copper busbar, namely a U-phase copper busbar (1.6.3), a V-phase copper busbar (1.6.4), and a V-phase copper busbar (1.6.5), and also integrates a fourth-phase copper busbar (1.6.6) and a filter magnetic ring (1.6.7).

9. The oil-cooled electric drive system according to claim 1, characterized in that: The motor stator (1.1) includes a stator core (1.1.1), a high-voltage copper busbar (1.1.2), a busbar assembly (1.1.3), and a stator temperature sensor (1.1.4); the high-voltage copper busbar (1.1.2) passes through the stator core (1.1.3). On 1.1.1), the busbar assembly (1.1.3) is connected to the upper end of the high-voltage copper busbar (1.1.2), and a square groove is provided on the busbar assembly (1.1.3). 1.1.3.1), the square-headed stator temperature sensor (1.1.4) is housed in the square groove (1.1.3.1) on the bus assembly (1.1.3) and fixed with potting compound. The stator temperature sensor (1.1.4) is located adjacent to the high-voltage copper busbar.

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