A multi-gear hub motor power unit based on an external rotor

Abstract

This invention relates to a multi-speed hub motor power unit based on an external rotor, mainly composed of a central shaft, hub, motor stator, motor rotor, front planetary gear train, rear planetary gear train, and first, second, and third clutches. The central shaft is fixed, the stator is fixedly connected to the central shaft, and the motor rotor is connected to the central shaft via two identical bearings. The motor rotor housing bearing abuts against the shaft shoulder for positioning. The motor rotor is fixedly connected to the planet carrier of the front planetary gear train and the input sun gear of the rear planetary gear train. The first clutch is fixedly connected to the central shaft, the second clutch is fixedly connected to the central shaft, and the third clutch is fixedly connected to the planet carrier of the rear planetary gear train and floatingly connected to the central shaft. Because the hub motor has multiple output speeds, the efficiency platform of the motor is greatly increased, allowing the motor to be installed in various types of vehicles, thus having greater applicability.

Description

Technical Field

[0001] This invention relates to a multi-speed hub motor power unit based on an external rotor. Technical Background

[0002] In recent years, with the deterioration of the environment and climate, countries around the world have paid increasing attention to environmental issues. my country has also introduced relevant policies to promote energy conservation and emission reduction, among which the transformation of automobiles to electric vehicles is an important plan. The hub motor used in some electric vehicles is one of their core technologies. Hub motors are generally divided into external rotor type and internal rotor type. Under the same volume, compared with the internal rotor motor, the external rotor motor has higher output torque and output power. At the same time, the external rotor has a larger surface area, which is conducive to heat dissipation during rotation. This is crucial for the compact structure of the hub motor. This invention proposes an external rotor type multi-speed hub motor for two-wheeled electric vehicles, elderly mobility scooters and micro electric vehicles commonly used in daily life.

[0003] Patent CN1889331A discloses a mechanism comprising an outer rotor of a motor and a planetary reduction gear transmission. Its features include a sun gear, several planetary gears, a ring gear, and a planet carrier. The outer rotor of the motor is fixedly connected to the sun gear, and the planetary gears drive the hub housing to rotate. This mechanism has a relatively high output power per unit weight and a relatively small mass. When there is no electricity and it is manually driven, the planetary reduction gear transmission mechanism and the outer rotor of the motor do not rotate, greatly reducing the force required to rotate the housing. The disadvantages of this mechanism are its relatively small size, difficulty in heat dissipation, and relatively low motor torque, making it unsuitable for electric vehicles with a large self-weight.

[0004] Patent CN112383186A discloses a hub motor that is easy to assemble. Its features include a main shaft, a stator fixed to the main shaft, a planetary carrier, and a gear ring disposed on the inner wall of the housing. The motor rotor is fixedly connected to the sun gear, and the rotor drives the sun gear to rotate as a reduction input. The planetary carrier is fixed to the main shaft, and the internal gear ring meshes with the planetary gears as the output. The advantage of this invention is that, compared with other installation methods, the axial positioning of each component no longer requires retaining rings; positioning is achieved by the component's own steps or shoulder end faces, greatly simplifying the installation steps and resulting in a compact structure. However, this mechanism only has one stage of reduction, making it difficult to apply to complex and varied road conditions.

[0005] Most common geared hub motors only have one reduction gear, which is sufficient for urban roads with good driving conditions. However, for some roads with poor driving conditions, the motor needs to provide a large enough torque, while only a small torque is needed on flat roads. There are very few such motors on the market. The hub motor designed in this invention has a simple structure and strong practicality. It can provide multiple torque outputs through the sequential engagement of the clutch, making it suitable for various types of vehicles. It has considerable development potential and broad prospects in the context of energy conservation and emission reduction. Summary of the Invention

[0006] To address the limitations of existing wheel hub motors on the market, such as limited gear selection, low versatility, small torque increase, and difficulty in adapting to complex road conditions, a multi-speed wheel hub motor power unit based on an external rotor was designed. This power unit can sequentially combine with different clutch shifting modules to achieve three different speed shifting functions. The principle is simple and clear, and the manufacturing process is convenient, providing a useful reference for the design of existing wheel hub motors.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention relates to a multi-speed hub motor power unit based on an external rotor, mainly composed of a transmission module, a reduction module, and a clutch shifting module. Specifically, it includes a central shaft, a return spring, a clutch piston, a clutch friction disc, a front sun gear, a motor rotor, a motor stator, a front first planetary gear, a front planetary carrier, a front second planetary gear, a front internal gear, a hub, an internal gear in the hub, a rear first planetary gear, a rear second planetary gear, a rear third planetary gear, a rear planetary carrier, a rear fourth planetary gear, a rear sun gear, a central shaft oil passage, a first clutch, a second clutch, and a third clutch.

[0009] The transmission module of this invention consists of front and rear planetary gear trains. The front planetary gear train comprises a front sun gear, a front planet carrier, a front first planetary gear, a front second planetary gear, and a front internal gear. The rear planetary gear train comprises a rear sun gear, a rear planet carrier, a hub internal gear, a rear first planetary gear, a rear second planetary gear, a rear third planetary gear, and a rear fourth planetary gear. The front sun gear meshes externally with the front first planetary gear, the front first planetary gear meshes externally with the front second planetary gear, and the front second planetary gear meshes internally with the front internal gear. The rear sun gear is fixedly connected to the motor rotor and meshes externally with the rear fourth planetary gear. The fourth planetary gear meshes externally with the third planetary gear in the rear row, the third planetary gear in the rear row meshes externally with the second planetary gear in the rear row, the second planetary gear in the rear row meshes externally with the first planetary gear in the rear row, and the first planetary gear in the rear row meshes internally with the gear inside the hub. The motor rotor is the input to the entire system unit. The front planetary carrier is fixedly connected to the motor rotor and is the input to the front planetary gear train. The front internal gear is fixedly connected to the rear planetary carrier and is the output of the front planetary gear train and the input of the rear planetary carrier. The rear sun gear is the input to the entire rear planetary gear train, and the gear inside the hub is the output of the entire system unit. The front sun gear, motor rotor, hub, and rear sun gear are all connected to the central shaft by bearings.

[0010] This invention uses a wet multi-plate clutch shifting module for gear shifting. The first, second, and third clutches in this invention have the same principle and structure. The oil in the central shaft drives the piston of the first clutch to move, so that the friction plate of the first clutch engages. After the clutch completes the engagement task, the return spring of the first clutch pushes the piston back. The working principle of the other clutches is the same. The first and second clutches are fixedly connected to the central shaft by splines. The third clutch is fixedly connected to the rear planetary carrier and is sealed to the central shaft by felt.

[0011] In this invention, the line connecting the axes of the first and second planetary gears in the front row does not pass through the center axis, and the line connecting the axes of the first, second, third, and fourth planetary gears in the rear row also does not pass through the center axis; that is, the branches of the front and rear planetary carriers are arranged in an arc shape. The hub bearing, the front sun gear bearing, and the motor rotor bearing are all positioned by the shoulder on the central axis.

[0012] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0013] 1. This invention uses front and rear planetary gear reduction modules for speed reduction and torque amplification, which effectively increases the torque of the hub motor and improves the vehicle's climbing ability. The entire reduction structure is designed inside the hub, eliminating the need for an additional reduction structure. Furthermore, the planetary gears of the front and rear planetary gear systems are arranged in an arc path during installation, resulting in a compact structure and significantly reducing the outer diameter of the motor.

[0014] 2. This invention uses three wet multi-plate clutch shifting modules for shifting. Compared with traditional synchronizer shifting, it eliminates a large number of transmission components. Shifting is driven by hydraulic oil, making operation simple and stable, and ensuring smooth and fast transmission shifting.

[0015] 3. The bearings of this invention are positioned by shoulder, eliminating the need for sleeve positioning, resulting in fewer parts and fewer installation steps. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the hub motor structure.

[0017] Figure 2 This is a simplified diagram of the first gear transmission route.

[0018] Figure 3 This is a simplified diagram of the second gear transmission route.

[0019] Figure 4 This is a simplified diagram of the third gear transmission route.

[0020] Figure 5 This is an enlarged view of the first clutch structure.

[0021] Figure 6 This is a diagram showing the arrangement of the front-row planetary gear system.

[0022] Figure 7 This is a diagram showing the arrangement of the rear planetary gear train.

[0023] The components are: 1. Central shaft; 2. First clutch return spring; 3. First clutch piston; 4. First clutch friction disc; 5. Front sun gear; 6. Motor rotor; 7. Motor stator; 8. Front first planetary gear; 9. Front planetary carrier; 10. Front second planetary gear; 11. Front internal gear; 12. Wheel hub; 13. Wheel hub internal gear; 14. Rear first planetary gear; 15. Rear second planetary gear; 16. Rear third planetary gear; 17. Rear planetary carrier; 18. Rear fourth planetary gear; 19. Rear sun gear; 20. Central shaft oil passage; A. First clutch; B. Second clutch; C. Third clutch. Detailed Implementation

[0024] This invention relates to a multi-speed hub motor power unit based on an external rotor, which mainly consists of a motor stator, a motor rotor, a reduction gear consisting of two rows of planetary gear trains, a three-speed wet multi-plate clutch shifting module, and an outer hub. See below for reference. Figure 1 The implementation method will be further explained.

[0025] In the transmission and reduction section, an electromagnetic coil is wound on the motor stator 7 and fixedly connected to the central shaft 1. When energized, it generates a magnetic field, driving the motor rotor 6 to rotate. The motor rotor 6 is also fixedly connected to the front planetary carrier 9 and the rear planetary carrier 17. Regarding the front planetary gear train, the front sun gear 5 is connected to the central shaft 1 by a bearing. The front first planetary gear 8 meshes externally with the front sun gear 5, the front second planetary gear 10 meshes externally with the front first planetary gear 8, and the front internal gear 11 meshes internally with the front second planetary gear 10. Simultaneously, the front planetary carrier 9 has an extended shaft fixedly connected to it, serving as the rotation center for the front second planetary gear 10 and the front first planetary gear 8. This is also the power input part of the front planetary gear train. The front internal gear 11 is fixedly connected to the extended shaft of the rear planetary carrier 17, serving as the output of the front planetary gear train. Regarding the rear planetary gear system, the rear sun gear 19 is the input of the rear planetary gear system. It is connected to the central shaft 1 by a bearing and meshes externally with the rear fourth planetary gear 18. The rear fourth planetary gear 18 meshes externally with the rear third planetary gear 16. The rear third planetary gear 16 meshes externally with the rear second planetary gear 15. The rear second planetary gear 15 meshes externally with the rear first planetary gear 14. The hub gear 13 meshes with the rear first planetary gear 14. The hub gear 13 and the hub 12 are a single unit, serving as the output of the entire power unit.

[0026] In the gear shifting section, the first clutch A and the second clutch B are fixedly connected to the central shaft 1, maintaining relative stillness, while the third clutch C is fixedly connected to the rear planetary carrier 17 and rotates with it. (Refer to...) Figure 5 An enlarged view of the first clutch A shows that hydraulic oil can enter the cavity of the first clutch A through the central shaft oil passage 20, pushing the first clutch piston 3 to move, which in turn pushes the first clutch friction discs 4 to rub against each other. Under the action of friction, engagement is completed. After the engagement movement is completed, the first clutch piston 3 can return under the elastic force of the first clutch return spring 2, releasing the engagement state. The engagement methods of other clutches are the same.

[0027] like Figure 6 The diagram shown is the arrangement of the front-row planetary gear system. Figure 7 The diagram shows the arrangement of the rear planetary gear train. In order to make better use of the space inside the wheel hub, the front and rear planetary carriers are designed in a spiral shape, making the structure of this wheel hub motor more compact.

[0028] The specific working principle of this invention is explained as follows:

[0029] Based on the actual road surface requirements for motor torque and speed, the gear parameters are designed as shown in Table 1 below, with each gear having a module m = 1 mm.

[0030]

[0031] The gear parameters in Table 1 and the engagement of different gear positions are shown in Table 2 below.

[0032]

[0033] Table 2 Clutch Gear Engagement

[0034] Note: "×" indicates separation, and "√" indicates joining.

[0035] Combination Figure 2 , Figure 3 , Figure 4 The transmission routes for each file are explained below:

[0036] 1. Climbing gear (D1):

[0037] like Figure 2 As shown, the rotation of the motor rotor drives the rear sun gear to rotate. At this time, the second clutch B is engaged, while the first clutch A and the third clutch C are disengaged. The central shaft 1 and the rear planetary carrier 17 are essentially a single unit, remaining relatively stationary. The entire reduction gear system is equivalent to a fixed-axis reduction gear train. The rear sun gear 19 sequentially transmits power to the rear fourth planetary gear 18, the rear third planetary gear 16, the rear second planetary gear 15, the rear first planetary gear 14, and the hub gear 13. The hub gear 13 is connected to the hub, ultimately driving the hub 12 to rotate. Its transmission ratio is 4, providing significant speed reduction and torque increase, and can be used as a climbing gear for vehicles.

[0038] 2. Acceleration mode (D2):

[0039] like Figure 3 As shown, the first clutch A is engaged, while the second clutch B and the third clutch C are disengaged. At this time, clutch A is equivalent to locking the front sun gear 5 to the central shaft 1, keeping the front sun gear 5 stationary. The front planetary carrier 9 is fixedly connected to the motor rotor 6 and has the same angular velocity, driving the front second planetary gear 10 and the front internal gear 11 to move. The front internal gear 11 is fixedly connected to the rear planetary carrier 17, transmitting power to the rear planetary carrier 17. The rear sun gear 19 transmits power sequentially through the rear fourth planetary gear 18, the rear third planetary gear 16, the rear second planetary gear 15, and the rear first planetary gear 14 to the rear wheel hub internal gear 13, driving the wheel hub 12 to rotate. The transmission ratio is 1.88. At this time, both torque and speed are in a moderate range, combining both torque and speed, and can be used for acceleration.

[0040] 3. Overtaking gear (D3):

[0041] like Figure 4 As shown, the third clutch C is engaged, while the first and second clutches are disengaged. At this time, the third clutch C is equivalent to locking the rear planetary carrier 19 and the rear sun gear 19 together, making them a single unit with the same angular velocity. In other words, the entire mechanism has the same angular velocity. The rear sun gear 19 transmits power sequentially through the rear fourth planetary gear 18, the rear third planetary gear 16, the rear second planetary gear 15, and the rear first planetary gear 14 to the rear wheel hub internal gear 13, which drives the wheel hub 12 to rotate. Ultimately, the angular velocity of the rear wheel hub 12 is the same as that of the rear sun gear 19, and the transmission ratio of the mechanism is 1. At this time, the wheel hub speed is at its maximum and the torque is at its minimum.

Claims

1. A multi-gear hub motor power unit based on an external rotor, characterized by, The multi-gear hub motor is mainly composed of a transmission module, a speed reduction module and a clutch shifting module, and comprises a central shaft (1), a first clutch reset spring (2), a first clutch piston (3), a first clutch friction disc (4), a front row sun gear (5), a motor rotor (6), a motor stator (7), a front row first planetary gear (8), a front row planet carrier, a front row second planetary gear (10), a front row inner gear, a hub (12), a hub inner gear (13), a rear row first planetary gear (14), a rear row second planetary gear (15), a rear row third planetary gear (16), a rear row planet carrier, a rear row fourth planetary gear (18), a rear row sun gear, a central shaft oil way (20), a first clutch, a second clutch and a third clutch. The transmission module is composed of the front and rear row planet carriers, the front row planetary gear train is composed of the front row sun gear (5), the front row planet carrier, the front row first planetary gear (8), the front row second planetary gear (10) and the front row inner gear, and the rear row planetary gear train is composed of the rear row sun gear, the rear row planet carrier, the hub inner gear (13), the rear row first planetary gear (14), the rear row second planetary gear (15), the rear row third planetary gear (16) and the rear row fourth planetary gear (18). The front row sun gear (5) is externally meshed with the front row first planetary gear (8), the front row first planetary gear (8) is externally meshed with the front row second planetary gear (10), and the front row second planetary gear (10) is internally meshed with the front row inner gear. The rear row sun gear is fixedly connected with the motor rotor (6), the rear row sun gear is externally meshed with the rear row fourth planetary gear (18), the rear row fourth planetary gear (18) is externally meshed with the rear row third planetary gear (16), the rear row third planetary gear (16) is externally meshed with the rear row second planetary gear (15), the rear row second planetary gear (15) is externally meshed with the rear row first planetary gear (14), and the rear row first planetary gear (14) is internally meshed with the hub inner gear (13). The motor rotor (6) is the input of the entire system unit, the front row planet carrier is fixedly connected with the motor rotor (6) and is the input of the front row planetary gear train, the front row inner gear is fixedly connected with the rear row planet carrier and is the output of the front row planetary gear train and the input of the rear row planet carrier, the rear row sun gear is the input of the entire rear row planetary gear train, the hub inner gear (13) is the output of the entire system unit, and the front row sun gear (5), the motor rotor (6), the hub (12) and the rear row sun gear are connected with the central shaft (1) through bearings.The wet multi-plate clutch shift module used for gear shifting, the first clutch, the second clutch and the third clutch have the same principle and structure. The oil in the center shaft (1) drives the first clutch piston (3) to move, so that the first clutch friction disc (4) is frictionally engaged. The first clutch return spring (2) pushes the first clutch piston (3) back after the clutch completes the engagement task. The first clutch and the second clutch are fixedly connected with the center shaft (1) by means of splines. The third clutch is fixedly connected with the rear planetary carrier and is connected with the center shaft (1) by means of felt sealing.

2. A multi-gear hub motor power unit based on external rotor according to claim 1, characterized in that, The hub (12) bearing, front row sun gear (5) bearing, motor rotor (6) bearing are positioned by the shaft shoulder on the center shaft (1).

3. The multi-gear hub motor power unit based on outer rotor type according to claim 1, characterized in that, The first clutch, the second clutch and the third clutch are driven and propelled by the hydraulic oil in the oil passage of the center shaft (1), and the hydraulic oil enters through three different routes of the oil passage (20) and works independently.

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