Gear box for coaxial electric drive axle
By dividing the coaxial gearbox into independent lubrication chambers for the mechanical and motor parts, the problem of concentrated meshing noise in the coaxial gearbox is solved, improving the overall vehicle NVH performance and user experience, while reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHANGSHU AAM AUTOMOTIVE DRIVELINE HIGH TECH MFG CO LTD
- Filing Date
- 2025-05-23
- Publication Date
- 2026-04-17
AI Technical Summary
The low viscosity of the lubricating oil in the coaxial gearbox leads to concentrated meshing noise, serious NVH problems, and affects the overall vehicle performance and user experience.
A separate lubrication scheme is adopted, dividing the gearbox into independent lubrication chambers for the mechanical and motor parts, using lubricating oils of different viscosities to lubricate them separately, forming a closed chamber structure.
The environmental damping of the gearbox is improved, meshing noise and gap collision noise are reduced, the overall NVH performance and user experience are improved, and the cost is reduced.
Smart Images
Figure CN224135145U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of electric vehicle related technology, specifically relating to a gearbox for a coaxial electric drive axle. Background Technology
[0002] The size and structure of the electric drive axle assembly of an electric vehicle directly affect the overall layout of the electric vehicle, and thus its overall performance. In order to improve the overall performance of electric vehicles, most existing coaxial electric drive axles adopt a common cavity lubrication system for the mechanical gearbox and motor. The original intention of this solution was to simplify the structural features of the gearbox housing, facilitate the lubrication of the entire axle, and reduce the types of oils. However, with the increasing application of coaxial electric axles in vehicles, it has been found that common cavity lubrication has many shortcomings and limitations. Therefore, it is necessary to further optimize and improve the design of the gearbox.
[0003] However, compared to other types of gearboxes, coaxial gearboxes have a closer center distance between the two stages of gears, resulting in a more compact structure. At the same time, the meshing points of the two stages of gears are also closer, making the noise during gear meshing more concentrated. In addition, the viscosity of the lubricating oil in coaxial gearboxes is much lower, resulting in lower environmental damping for the entire gearbox. During the start-stop process of the electric axle, the meshing noise of the gears and the noise from the gap collision cannot be absorbed by the damping. Compared with traditional gearboxes that use higher viscosity lubricating oil, the knocking sound of the coaxial axle is clearer, which in turn affects the NVH (noise, vibration, and harshness) of the entire vehicle and the actual user experience. Utility Model Content
[0004] The purpose of this invention is to provide a gearbox for a coaxial electric drive axle, in order to solve the problems mentioned in the background art. Compared with other types of gearboxes, the center distance between the two stages of a coaxial gearbox is closer, resulting in a more compact structure. At the same time, the meshing points of the two stages of gears are also closer, resulting in a more concentrated noise during gear meshing. In addition, the viscosity of the lubricating oil in a coaxial gearbox is much lower, so the environmental damping of the entire gearbox is also lower. During the start-stop process of the electric axle, the meshing noise and gap collision noise of the gears cannot be absorbed by the damping. Compared with traditional gearboxes that use higher viscosity lubricating oil, the knocking sound of the coaxial axle is clearer, which affects the NVH of the whole vehicle and the actual user experience.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a gearbox for a coaxial electric drive axle, comprising a gearbox motor part and a gearbox mechanical part;
[0006] The gearbox motor section has a right motor housing on its outer side, and the gearbox mechanical section has a left motor housing on its outer side. An input shaft is located in the center of the gearbox motor section. A rotating shaft sleeve is located on the outer side of the input shaft. A left half-shaft is located on the left side inside the rotating shaft sleeve, and a right half-shaft is located on the right side inside the rotating shaft sleeve. A primary drive gear is located on the outer side of the right half-shaft. A tail double-lip oil seal is located at the left end of the input shaft, and a head double-lip oil seal is located at the right end of the input shaft. A rotor is located on the outer side of the input shaft. An input shaft tail bearing is located on the outer side of the left end of the input shaft, and an input shaft head bearing is located on the outer side of the right end of the input shaft.
[0007] Preferably, the input shaft passes through the gearbox motor section, and from left to right, a tail double-lip oil seal, an input shaft tail bearing, an input shaft head bearing, and a head double-lip oil seal are installed on the outer side of the input shaft to form an isolation between the gearbox mechanical lubrication cavity and the motor lubrication cavity.
[0008] Preferably, the input shaft tail bearing and the input shaft head bearing can cooperate with the middle input shaft to rotate, and the input shaft is driven by a rotor arranged on the outer side.
[0009] Preferably, the gearbox motor part and the gearbox mechanical part are respectively encapsulated by the right motor housing and the left motor housing, and the end caps of the right motor housing and the left motor housing are respectively provided with oil seal mating surfaces to support the oil seal mating, forming two sealed cavities.
[0010] Preferably, the left and right housings of the motor are fixedly installed together by fasteners, and a rotating shaft sleeve is provided on the outer side of the left half shaft rod, which is sleeved with the left half shaft rod.
[0011] Preferably, a primary drive gear is provided on the outer side of the right half shaft, and the primary drive gear meshes with a primary driven gear.
[0012] Preferably, the secondary driven gear meshes with the secondary driving gear, the secondary driven gear is fixedly connected to the outer periphery of the differential housing, and the secondary driven gear can contact the lubricating oil accumulated in the lower part of the housing.
[0013] Compared with the prior art, the present invention provides a gearbox for a coaxial electric drive axle, which has the following advantages:
[0014] 1. The purpose of this invention is to optimize and improve the common cavity lubrication of the gearbox in a coaxial electric axle by changing it to a separate cavity lubrication scheme. This allows the motor and mechanical transmission parts to be lubricated separately with different types of oil. This invention solves a series of problems and troubles caused by the current common oil lubrication of the coaxial gearbox and motor, such as noise during vehicle start-up and stop, and reduced gear fatigue life. After separate cavity lubrication, the viscosity of the gear oil increases, thereby increasing the damping of the entire gearbox system environment. During the start-up and stop of the electric axle, the meshing noise and gap collision noise of the gears will be greatly absorbed by the damping, thereby improving the NVH (noise, vibration, and harshness) performance of the vehicle and the actual user experience.
[0015] 2. Conventional gear lubricants and motor lubricants on the market are already very mature applications. The lubrication of the cavity avoids the need to develop new high-cost oils, further reducing costs. In addition, the use of specialized gear lubricants and motor lubricants can fully guarantee the service life and lubrication effect of gears and motors. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the coaxial gearbox common cavity lubrication scheme of this utility model.
[0017] Figure 2 This is a schematic diagram of the lubrication scheme for the coaxial gearbox cavity of this utility model.
[0018] Figure 3 This is a schematic diagram of the cavity structure oil seal of this utility model.
[0019] In the diagram: 1. Gearbox motor section; 2. Right motor housing; 3. Gearbox mechanical parts; 4. Differential; 5. Shaft sleeve; 6. Input shaft tail bearing; 7. Tail double-lip oil seal; 8. Head double-lip oil seal; 9. Rotor; 10. Input shaft head bearing; 11. First-stage drive gear; 12. Second-stage driven gear; 13. Left motor housing; 14. Left half shaft; 15. Right half shaft; 16. Input shaft. Detailed Implementation
[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0021] This utility model provides, for example Figure 1-3 The gearbox shown is for a coaxial electric drive axle, including a gearbox motor part 1 and a gearbox mechanical part 3;
[0022] The gearbox motor section 1 has a right motor housing 2 on its outer side, and the gearbox mechanical section 3 has a left motor housing 13 on its outer side. The gearbox motor section 1 has an input shaft 16 in the middle inside, and a rotating shaft sleeve 5 on its outer side. The rotating shaft sleeve 5 has a left half shaft 14 on its left side and a right half shaft 15 on its right side. The right half shaft 15 has a first-stage drive gear 11 on its outer side. The left end of the input shaft 16 has a tail double-lip oil seal 7, and the right end of the input shaft 16 has a head double-lip oil seal 8. The input shaft 16 has a rotor 9 on its outer side, the left end of the input shaft 16 has an input shaft tail bearing 6 on its outer side, and the right end of the input shaft 16 has an input shaft head bearing 10 on its outer side.
[0023] In this embodiment, the gearbox of the coaxial electric drive axle is its core transmission component. It is mainly responsible for converting the high-speed, low-torque output of the motor into a low-speed, high-torque output suitable for wheel drive, while realizing power transmission and structural integration. The rotor shaft of the motor is directly connected to the input shaft 16 of the gearbox through a spline or flange. The input shaft 16 drives the first-stage driving gear 11 and the second-stage driven gear 12 to reduce speed and increase torque. Due to the coaxial design, the output shaft of the motor and the drive shaft of the axle are on the same center line. After the power is reduced by the gearbox, it is distributed to the left half shaft 14 and the right half shaft 15 through the differential 4, and finally drives the wheels to rotate.
[0024] like Figure 2 and Figure 3 As shown, the input shaft 16 passes through the gearbox motor section 1. From left to right, a tail double-lip oil seal 7, an input shaft tail bearing 6, an input shaft head bearing 10, and a head double-lip oil seal 8 are sequentially installed on the outer side of the input shaft 16, forming an isolation between the gearbox mechanical lubrication chamber and the motor lubrication chamber. The input shaft tail bearing 6 and the input shaft head bearing 10 can rotate in conjunction with the middle input shaft 16. The input shaft 16 is driven by the rotor 9 located on the outer side. The gearbox motor section 1 and the gearbox mechanical section 3 are respectively encapsulated by the right motor housing 2 and the left motor housing 13. The right motor housing 2 and the left motor housing 13... The end caps of the housing are respectively provided with oil seal mating surfaces to support the oil seal mating, forming two sealed cavities. The left housing 13 and the right housing 2 of the motor are fixedly installed by fasteners. A rotating shaft sleeve 5 is provided on the outside of the left half shaft 14, and the rotating shaft sleeve 5 is sleeved with the left half shaft 14. A first-stage driving gear 11 is provided on the outside of the right half shaft 15. The first-stage driving gear 11 meshes with the first-stage driven gear. The second-stage driven gear 12 meshes with the second-stage driving gear. The second-stage driven gear 12 is fixedly connected to the outer periphery of the housing of the differential 4. The second-stage driven gear 12 can contact the lubricating oil accumulated in the lower part of the housing.
[0025] Preferably, by setting a head double-lip oil seal 8 and a tail double-lip oil seal 7, the coaxial electric drive axle gearbox has undergone structural improvement based on the original gearbox housing. First, a head double-lip oil seal 8 is added after the input shaft head bearing 10 to isolate oil circulation between the mechanical and motor parts, achieving separate cavity lubrication. Second, a tail double-lip oil seal 7 is added after the input shaft tail bearing 6 to isolate any oil that may appear on the input hollow shaft and the motor hollow shaft. Finally, the motor housing and end cover are optimized by adding oil seal mating surfaces to support the oil seal mating. Through structural optimization, two sealed cavities are formed, thereby achieving separate cavity lubrication for the mechanical gearbox part and the motor part. After separate cavity lubrication, the viscosity of the gear oil increases, thereby increasing the damping of the entire gearbox system environment. During the start-stop process of the electric axle, the meshing noise of the gears and the gap collision noise will be greatly absorbed by the damping, thereby improving the overall NVH performance of the vehicle and the actual user experience.
[0026] Preferably, because the heat dissipation requirements of the motor are relatively high, the viscosity of the motor lubricating oil cannot be too high. However, the operation of mechanical parts such as gears and bearings requires lubricating oil with higher viscosity. Therefore, in order to balance the working environment and performance of both, it is necessary to develop and test special oils. By adjusting the oil formula, it can be used for lubrication of both, which is costly. Secondly, the viscosity of newly developed oils will be reduced accordingly because they take into account the lubrication performance of the motor. This poses a greater challenge to the operation of gears and bearings in the mechanical part 3 of the gearbox. At the same time, low viscosity oils have a greater impact on gear life. The gearbox's chamber lubrication solution is much better because conventional gear lubricating oils and motor lubricating oils are already very mature in the market. Chamber lubrication avoids the development of new high-cost oils, further reducing costs. Furthermore, the use of specialized gear lubricating oils and motor lubricating oils can comprehensively ensure the service life and lubrication effect of gears and motors.
[0027] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A gearbox for a coaxial electric drive axle, comprising a gearbox motor part (1) and a gearbox mechanical part (3) and a secondary driven gear (12); characterized in that The gearbox motor part (1) is provided with a right motor housing (2) on the outside, the gearbox mechanical part (3) is provided with a left motor housing (13) on the outside, the gearbox motor part (1) is provided with an input shaft (16) in the middle inside, the input shaft (16) is provided with a rotating shaft sleeve (5) on the outside, the rotating shaft sleeve (5) is provided with a left half shaft rod (14) on the left side inside, the rotating shaft sleeve (5) is provided with a right half shaft rod (15) on the right side inside, the right half shaft rod (15) is provided with a first-stage drive gear (11) on the outside, the input shaft (16) is provided with a tail double-lip oil seal (7) on the left end, the input shaft (16) is provided with a head double-lip oil seal (8) on the right end, the input shaft (16) is provided with a rotor (9) on the outside, the input shaft (16) is provided with an input shaft tail bearing (6) on the outside of the left end, and the input shaft (16) is provided with an input shaft head bearing (10) on the outside of the right end.
2. A gearbox for a coaxially electrically driven axle according to claim 1, characterized in that: The input shaft (16) passes through the gearbox motor part (1). From left to right, the input shaft (16) is equipped with a tail double lip oil seal (7), an input shaft tail bearing (6), an input shaft head bearing (10), and a head double lip oil seal (8), forming a separation between the gearbox mechanical lubrication cavity and the motor lubrication cavity.
3. A gearbox for an electrically driven axle of the coaxial type according to claim 2, characterized in that: The input shaft tail bearing (6) and input shaft head bearing (10) can rotate in conjunction with the middle input shaft (16), which is driven by the rotor (9) arranged on the outside.
4. A gearbox for an electrically driven axle of the coaxial type according to claim 3, characterized in that: The gearbox motor part (1) and the gearbox mechanical part (3) are respectively encapsulated by the right motor housing (2) and the left motor housing (13). The end caps of the right motor housing (2) and the left motor housing (13) are respectively provided with oil seal mating surfaces to support oil seal mating, forming two sealed cavities.
5. A gearbox for an electrically driven axle of the coaxial type according to claim 4, characterized in that: The left housing (13) and the right housing (2) of the motor are fixedly installed together by fasteners. A rotating shaft sleeve (5) is provided on the outside of the left half shaft (14), and the rotating shaft sleeve (5) is sleeved with the left half shaft (14).
6. A gearbox for an electrically driven axle of the coaxial type according to claim 5, characterized in that: A primary drive gear (11) is provided on the outer side of the right half shaft (15), and the primary drive gear (11) meshes with the primary driven gear.
7. A gearbox for an electrically driven axle of the coaxial type according to claim 6, characterized in that: The secondary driven gear (12) meshes with the secondary driving gear. The secondary driven gear (12) is fixedly connected to the outer periphery of the housing of the differential (4). The secondary driven gear (12) can contact the lubricating oil accumulated in the lower part of the housing.