A multi-gear variable speed wheel hub motor power assembly containing an ultra-speed stage

Abstract

This invention discloses a multi-speed hub motor powertrain with an overspeed stage, mainly composed of a fixed shaft, hub, motor stator, motor rotor, first planetary gear train, second planetary gear train, and three clutches. The hub forms a receiving cavity. The stator is fixedly connected to the fixed shaft. The motor rotor is connected to the rear of the fixed shaft via two identical bearings. The motor rotor is fixedly connected to the planet carrier of the first planetary gear train and the input sun gear of the second planetary gear train. The first clutch is fixedly connected to the fixed shaft, the second clutch is fixedly connected to the fixed shaft, and the third clutch is fixedly connected to the planet carrier of the second planetary gear train and floatingly connected to the fixed shaft. This invention achieves different gears by changing the order of engagement of the three clutches, enabling the motor to have three different transmission ratios. It has advantages such as compact structure and simple implementation method. It has an overspeed function on flat roads, which can improve the efficiency of motor use and has certain practical value.

Description

Technical Field

[0001] This invention belongs to the field of multi-speed hub motors, specifically relating to a hub motor for electric vehicles. Technical Background

[0002] Hub motors have been around for a long time, and with the global promotion of new energy vehicles, research on hub motors has also surged. A hub motor integrates the power system and transmission system, directly driven by electricity, eliminating many transmission components. It offers good starting response and low manufacturing cost, and is widely used not only in two-wheeled electric vehicles but also in micro electric vehicles, mobility scooters for the elderly, and special-purpose vehicles. As hub motors are continuously optimized and promoted, their applications are expanding. However, they often fail to meet power demands in complex road conditions. While traditional two-wheeled electric vehicles have climbing, flat, and overtaking gears, these are merely simulated gears achieved by adjusting the speed limit through a controller. The motor's torque can only be fine-tuned by voltage adjustments, without a significant change in torque. Even high-speed motors using single-stage reduction output, while increasing torque, still lack a single transmission ratio, making it difficult to meet real-world requirements in complex road conditions.

[0003] Patent CN108242866B discloses an external rotor geared motor, characterized by a two-stage reduction planetary gear and a motor section. This hub motor connects two planetary gear trains in series. The motor rotor is fixedly connected to the first-stage sun gear as input, and the first-stage planetary carrier serves as the input to the second-stage sun gear. Finally, the second-stage planetary carrier is connected to the hub for power output. This method is simple in principle and easy to manufacture. By using a two-stage planetary carrier as the output, it can reduce the speed of a high-speed motor and increase its torque, thus achieving a large reduction ratio, making it suitable for applications with steep gradients. However, this invention has a large reduction ratio and only a single reduction ratio, resulting in a low hub speed after reduction, which is insufficient for daily acceleration and overtaking needs.

[0004] Patent CN101056031B discloses a hub motor with built-in power generation. Its features include a rotor that rotates with the hub sleeve, a stator located on the hub shaft, and a magnet base with magnet plates. This invention combines a motor with a power generation device, employing a low-speed motor. The motor rotor, while rotating, cuts magnetic lines of force to generate current. The structure is compact and lightweight, making it suitable for electric bicycles with limited portable power supplies. However, due to the added power generation device, it experiences additional magnetic resistance compared to conventional motors, resulting in lower output torque, higher moment of inertia, slower starting speed, and lower motor efficiency during extended riding.

[0005] Most external rotor hub motors currently on the market are single-unit reduction gears, resulting in a narrow efficiency range and making them unsuitable for road surfaces requiring high torque variation, such as steep mountain roads or heavy-load electric vehicles and vehicles for the elderly. Single-stage hub motors designed for high speeds typically also have high output torque, leading to energy waste and low efficiency on flat roads where torque requirements are lower. Therefore, designing a multi-speed hub motor powertrain with an overspeed stage to meet the power and speed demands under different operating conditions would have significant social benefits. Summary of the Invention

[0006] To address the shortcomings of existing electric vehicles, such as insufficient gear shifting, limited torque and speed options, and difficulty in adapting to complex road conditions, a multi-speed hub motor powertrain with an overspeed stage was designed based on practical needs. This power unit can achieve three different gear shifting functions through the sequential engagement of three clutches. The principle is simple and clear, and the manufacturing process is convenient, providing a useful reference for the design of existing 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 powertrain with an overspeed stage, comprising a fixed shaft, a hub, a first sun gear, a motor rotor, first planetary gear train planetary gears, first planetary gear train internal gears, hub internal gears, second planetary gear train first planetary gears, second planetary gear train second planetary gears, a motor stator, a second sun gear, a second clutch steel plate, a second clutch piston, a second clutch return spring, a second clutch friction plate, a fixed shaft oil passage, a second planetary carrier, a first planetary carrier, a first clutch, a second clutch, and a third clutch.

[0009] The power transmission module of this invention consists of two planetary gear systems. The first planetary gear system comprises a first sun gear, a first planet carrier, first planetary gears of the first planetary system, and an internal gear of the first planetary gear system. The second planetary gear system comprises a second sun gear, a second planet carrier, second planetary gears of the second planetary gear system, first planetary gears of the second planetary gear system, and an internal gear in the hub. The first sun gear meshes externally with the planetary gears of the first planetary gear system, and the internal gear of the first planetary gear system meshes internally with the planetary gears of the first gear system. The second sun gear is fixedly connected to the motor rotor, and the second planetary sun gear meshes with the second... The second planetary gear of the planetary gear train is externally meshed, and the second planetary gear of the second planetary gear train is externally meshed with the first planetary gear of the second planetary gear train. The hub gear is internally meshed with the first planetary gear of the second planetary gear train. The motor rotor is the input of the entire system unit. The first planetary carrier is fixedly connected to the motor rotor and is the input of the first planetary gear train. The hub gear is the output of the first planetary gear train. Similarly, the second sun gear is the input of the second planetary gear train, and the hub gear is the output of the entire system unit. The first sun gear, the second sun gear, and the motor rotor are all connected to the fixed shaft by bearings.

[0010] This invention utilizes a dry multi-plate clutch shifting module for gear shifting. All three clutches in this invention operate on the same principle. Oil in the fixed shaft's oil circuit enters the oil chambers of the first, second, and third clutches, pushing the clutch pistons to move. This causes the clutch plates to engage and rub against the friction plates until they are fully engaged. A clutch return spring pushes the pistons back to their original position. The first and second clutches are fixedly connected to the fixed shaft via splines. The third clutch is fixedly connected to the second planetary carrier and floats with a sealing ring to the fixed shaft. In the second planetary gear train, the planetary gears and the lines connecting their shaft centers do not pass through the centerline of the fixed shaft. Each bifurcation of the second planetary carrier has a specific arc shape.

[0011] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0012] 1. This invention uses three dry multi-plate clutch shifting modules to complete the shifting task. Compared with the traditional synchronizer shifting, it eliminates a large number of transmission components. Shifting is driven by hydraulic oil, making operation simple and ensuring the smoothness and speed of transmission shifting.

[0013] 2. This invention uses two rows of planetary gears to complete the deceleration task. The entire deceleration structure is built into the hub, saving the need for additional deceleration devices. The number of gear teeth is appropriately designed, and the planetary gears of the second-stage planetary gear system are arranged in an arc path during installation, resulting in a compact structure and greatly reducing the size of the motor.

[0014] 3. This invention adopts an external rotor multi-speed reduction, which has good heat dissipation performance. Compared with the same horizontal geared motor, it has three transmission ratios, which can better meet the torque and vehicle speed requirements. It is stable and reliable, simple to process and manufacture, and highly practical. It can be used in various types of vehicles. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the hub motor structure.

[0016] Figure 2 This is a simplified diagram of the first gear transmission route.

[0017] Figure 3 This is a simplified diagram of the second gear transmission route.

[0018] Figure 4 This is a simplified diagram of the third gear transmission route.

[0019] Figure 5 This is an enlarged view of the second clutch B structure.

[0020] Figure 6 This is a diagram of the second-order planetary gear system.

[0021] The components are: 1. Fixed shaft; 2. Hub; 3. First sun gear; 4. Motor rotor; 5. First planetary gear train planetary gears; 6. First planetary gear train internal gear; 7. Hub internal gear; 8. Second planetary gear train first planetary gear; 9. Second planetary gear train second planetary gear; 10. Motor stator; 11. Second sun gear; 12. Second clutch steel plate; 13. Second clutch piston; 14. Second clutch return spring; 15. Second clutch friction plate; 16. Fixed shaft oil passage; 17. Second planetary carrier; 18. First planetary carrier; A. First clutch; B. Second clutch; C. Third clutch. Detailed Implementation

[0022] This invention relates to a multi-speed hub motor powertrain with an overspeed stage, which mainly consists of a motor stator, a motor rotor, a reduction gear consisting of two rows of planetary gears, a three-speed dry multi-plate clutch, and an outer hub. See below for reference. Figure 1 The implementation method will be further explained.

[0023] In the transmission and reduction section, an electromagnetic coil is wound on the motor stator 10 and fixedly connected to the fixed shaft 1. When energized, it generates a magnetic field, driving the motor rotor 4 to rotate. The motor rotor 4 is also fixedly connected to the first planetary carrier 18 and the second sun gear 11. Regarding the first planetary gear train, the first sun gear 3 is connected to the fixed shaft 1 by a bearing. The planet gears 5 of the first planetary gear train mesh externally with the first sun gear 3, and the internal gear 6 of the first planetary gear train meshes internally with the planet gears 5. Simultaneously, the first planetary carrier 18 has an extended shaft that serves as the rotation center of the planet gears 5 and is also the input of the first planetary gear train. The internal gear 6 of the first planetary gear train is fixedly connected to the extended shaft of the second planetary carrier 17, serving as the output of the first planetary gear train. Regarding the second planetary gear train, the second sun gear 11 is the input of the second planetary gear train, connected to the fixed shaft 1 by a bearing, and externally meshes with the second planet gear 9 of the second planetary gear train. The first planet gear 8 of the second planetary gear train externally meshes with the second planet gear 9 of the second planetary gear train, and the hub gear 7 internally meshes with the first planet gear 8 of the second planetary gear train. The hub gear 7 and the hub 2 are a single unit, serving as the output of the entire power unit. The left half of the second clutch B is fixedly connected to the second planetary carrier 17, and the second sun gear 11 is fixedly connected to the left half of the third clutch C.

[0024] In the gear shifting section, the first clutch A and the second clutch B are keyed to the fixed shaft 1, maintaining relative stillness, while the third clutch C is fixed to the second planetary carrier 17 and rotates therewith. (Refer to...) Figure 5 An enlarged view of the second clutch B shows that hydraulic oil can enter the clutch cavity through the fixed shaft oil passage 16, pushing the second clutch piston 13 to move, which in turn pushes the second clutch steel plate 12 to move. Under the action of friction, it engages with the second clutch friction plate 15. After the engagement movement is completed, the second clutch piston 13 can return to its original position under the elastic force of the second clutch return spring 14, thus disengaging the engagement state.

[0025] Planetary support section, Figure 6 The diagram shows the arrangement of the second planetary gear train. The planet carrier support is bifurcated in an approximately arc-shaped distribution. This structural design can significantly reduce the space occupied by the planet carrier, making the invention more compact.

[0026] The specific working principle of this invention is explained as follows:

[0027] Based on the actual road surface requirements for motor torque and speed, the gear parameters are designed as shown in the table below, with each gear having a module m = 1 mm.

[0028] Table 1 Gear Parameters

[0029]

[0030] The execution of different gear engagements is shown in Table 2 below.

[0031] Table 2 Clutch Gear Engagement

[0032]

[0033] Note: "×" indicates separation, and "√" indicates joining;

[0034] Combination Figure 2 , Figure 3 , Figure 4 The transmission routes for each file are explained below:

[0035] 1. First gear (D1):

[0036] like Figure 2 As shown, the rotation of the motor rotor drives the second 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 fixed shaft 1 and the second planetary carrier 17 are essentially a single unit, remaining relatively stationary. The entire reduction gear is equivalent to a fixed-axis reducer. The second sun gear 11 sequentially transmits power to the second planetary gear 9, the first planetary gear 8, and the hub gear 7 of the second planetary gear train. Finally, the hub gear 7 connects to the hub, driving the hub 2 to rotate. Its transmission ratio is 2.5, providing both speed reduction and torque increase.

[0037] 2. Second gear (D2):

[0038] like Figure 3 As shown, the third clutch C is engaged, while the first clutch A and the second clutch B are disengaged. At this time, the third clutch C is equivalent to locking the second planetary carrier 17 and the second sun gear 11 together. The two are equivalent to a whole and have the same angular velocity, that is, the entire mechanism has the same angular velocity. The second sun gear 11 transmits power sequentially through the second planetary gear 9 and the first planetary gear 8 of the second planetary gear system to the gear 7 inside the hub. Finally, the angular velocity of the hub 2 is the same as that of the sun gear, and the transmission ratio of the mechanism is 1.

[0039] 3. Third gear (D3):

[0040] like Figure 4As shown, the first clutch A is engaged, while the second clutch B and the third clutch C are disengaged. At this time, the first clutch A locks the first sun gear 3 to the fixed shaft 1, keeping the first sun gear 3 stationary. The first planetary carrier 18 is fixedly connected to the motor rotor 4 and has the same angular velocity, driving the planetary gears 5 and the internal gear 6 of the first planetary gear train to move. The internal gear 6 of the first planetary gear train is fixedly connected to the extended shaft on the second planetary carrier 17, transmitting power to the second planetary carrier 17. The second sun gear 11 transmits power sequentially through the second planetary gear 9 and the first planetary gear 8 of the second planetary gear train to the internal gear 7 of the hub, driving the hub 2 to rotate. Its transmission ratio is 0.68, which has a speed-up function.

Claims

1. A multi-gear variable speed wheel hub motor power assembly containing an overspeed stage, comprising a fixed shaft (1), a wheel hub (2), a first sun gear (3), a motor rotor (4), a first planetary gear system planetary gear (5), a first planetary gear system ring gear (6), a wheel hub ring gear (7), a second planetary gear system first planetary gear (8), a second planetary gear system second planetary gear (9), a motor stator (10), a second sun gear (11), a second clutch (B) steel sheet (12), a second clutch (B) piston (13), a second clutch (B) return spring (14), a second clutch (B) friction plate (15), a fixed shaft oil way (16), a second carrier (17), a first carrier (18), a first clutch (A), a second clutch (B), a third clutch (C); the multi-gear variable speed wheel hub motor power assembly containing an overspeed stage, characterized in that, The power transmission module is composed of two groups of planetary gear trains, the first planetary gear train is composed of a first sun gear (3), a first carrier (18), a first planetary gear train planetary gear (5), a first planetary gear train ring gear (6), the second planetary gear train is composed of a second sun gear (11), a second carrier (17), a second planetary gear train second planetary gear (9), a second planetary gear train first planetary gear (8) and a hub ring gear (7), wherein the first sun gear (3) is externally meshed with the first planetary gear train planetary gear (5), and the first planetary gear train ring gear (6) is internally meshed with the first planetary gear train planetary gear (5); the second sun gear (11) is fixedly connected with the motor rotor (4), the second sun gear (11) is externally meshed with the second planetary gear train second planetary gear (9), the second planetary gear train first planetary gear (8) is externally meshed with the second planetary gear train second planetary gear (9), and the hub ring gear (7) is internally meshed with the second planetary gear train first planetary gear (8); wherein the motor rotor (4) is the input of the entire system unit, the first carrier (18) is fixedly connected with the motor rotor (4) and is the input of the first planetary gear train, the first planetary gear train ring gear (6) is the output of the first planetary gear train, and the second sun gear (11) is the input of the second planetary gear train, the hub ring gear (7) is the output of the entire system unit, and the first sun gear (3), the second sun gear (11) and the motor rotor (4) are connected with the fixed shaft (1) through bearings; the multi-gear variable speed wheel hub motor power assembly with an overspeed stage is characterized in that a dry multi-plate clutch shifting module is used for gear shifting, wherein the oil in the fixed shaft oil way (16) enters the second clutch (B) oil chamber to push the second clutch (B) piston (13) to move, so that the second clutch (B) steel sheet (12) and the second clutch (B) friction plate (15) are mutually engaged and rubbed until combined, and the second clutch (B) return spring (14) is responsible for pushing the second clutch (B) piston (13) to return, the first clutch (A) and the second clutch (B) are fixedly connected with the fixed shaft (1) through splines, the third clutch (C) is fixedly connected with the second carrier (17) and is connected with the fixed shaft (1) through a floating sealing ring; the multi-gear variable speed wheel hub motor power assembly with an overspeed stage is characterized in that the second planetary gear train first planetary gear (8) and the second planetary gear train second planetary gear (9) in the second planetary gear train do not pass through the center line of the fixed shaft (1), and each fork of the second planetary gear train carrier has a certain circular arc shape.

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