Three-gear variable speed wheel hub motor power assembly containing large torque

Abstract

The application discloses a three-gear variable-speed wheel hub motor power assembly containing a large torque, and is characterized by comprising a motor, a left planetary gear train, a right planetary gear train, a first brake, a second brake, a third brake and a wheel hub, wherein the first brake and the second brake are fixedly connected to the inner wall of a machine box, the third brake is fixedly connected to the motor shaft, and the three brakes realize gear switching function through mutual cooperation. The application can satisfy three forward gears, one neutral gear and one parking gear, wherein the three forward gears contain one large torque gear; meanwhile, the application has the characteristics of compact structure, simple gear shifting mode, high transmission efficiency and low assembly precision requirement and the like, provides a new scheme reference for the transmission structure of the existing wheel hub motor of a load electric vehicle, and has good use value and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle hub motors, specifically relating to a high-torque three-speed hub motor powertrain. Background Technology

[0002] In-wheel motors play a crucial role in many electric vehicles. They integrate the power unit and transmission system inside the wheel, greatly simplifying the electric vehicle's power system and allowing the electric motor's power to be directly transmitted to the wheel, reducing losses from mechanical transmission. my country is also in a phase of vigorous development in heavy-duty electric vehicles. The in-wheel motors used in heavy-duty trucks have even stricter requirements for output torque, demanding not only smooth output but also a certain climbing ability. Moreover, the operating environment of heavy-duty trucks is much harsher than that of ordinary electric vehicles, with many operating in remote areas or mountainous regions with steep inclines and even unpaved roads. Such usage scenarios place extremely high demands on the torque of the in-wheel motor. Secondly, heavy-duty trucks are heavy and have a large load capacity, requiring them to overcome significant inertia during start-up and shutdown. Without sufficient torque output, they may not be able to start quickly. Thirdly, heavy-duty trucks are not always carrying cargo. During off-duty periods, the demand for torque is less pronounced. Relying solely on speed control not only wastes energy but also poses driving safety issues.

[0003] For the reasons mentioned above, the speed-changing performance and high-torque output performance of wheel hub motors for heavy-duty trucks are crucial. Considering the ease of adjusting the transmission ratio and shifting gears of planetary gear systems, combining the wheel hub motor with a planetary gear system allows for the design of a three-speed variable wheel hub motor with high torque, incorporating both a planetary gear system and a brake, to solve the aforementioned problems.

[0004] Patent CN 109130837 A discloses a low-speed, high-torque electric wheel device, characterized by a hub motor, a first planetary gear set, and a second planetary gear set. This invention utilizes the power output from the hub motor, through a two-stage planetary gear reduction mechanism, to achieve a low-speed, high-torque effect at the wheel hub, thus improving the power performance of electric wheel-driven vehicles. However, its structure lacks a gear-changing function; speed and torque cannot be simultaneously achieved, failing to meet the variable torque output requirements of heavy-duty electric vehicles.

[0005] Patent CN 108075603 A discloses a hub motor, characterized by providing a novel variable-speed hub motor. It proposes and solves a solution for achieving dual-power speed change and air-cooling at higher hub motor power levels. This solution can be used for single-wheel drive in high-power electric-assisted cargo bicycles and is also suitable for high-power pure electric motorcycles. However, it only allows manual shifting, lacks the reliability of hydraulic systems, and its structure is only suitable for electric bicycles or electric motorcycles, making it impractical in the electric vehicle field.

[0006] Patent CN108242866A discloses a hub motor employing a two-stage planetary gear system. This hub motor features a first-stage planetary gear reduction mechanism and a second-stage planetary gear reduction mechanism, increasing the reduction ratio and the motor's output torque, thereby increasing the motor's efficiency plateau and enabling it to adapt to different road conditions with stronger driving force. However, it does not fully utilize the flexible transmission ratio characteristics of planetary gear systems, lacks speed-changing capabilities, has poor practicality, and provides only a small increase in torque, making it unsuitable for heavy-duty trucks that require high torque.

[0007] Current hub motors mostly use single-stage gear transmission with a single reduction ratio, and their output torque is not maximized for heavy-duty vehicles, making it difficult to meet the complex and varied power demands of heavy-duty electric vehicles. They also cannot achieve good motor efficiency on non-load-bearing roads and steep inclines. Therefore, this invention, after fully considering these factors, integrates the planetary gear system with the brake, increasing the number of transmission gears in the hub motor, thus better meeting the power needs of heavy-duty electric vehicles operating under different road conditions. Summary of the Invention

[0008] Existing electric vehicle hub motor power units suffer from a single output transmission ratio, lack of high torque output capability, and inability to maintain high efficiency under extreme conditions, thus failing to meet complex and varied operational requirements. This invention utilizes two planetary gear sets and three brakes to achieve a three-speed output for the motor, providing three variable transmission ratios, including one high-torque output ratio. The shifting operation is simple, and the transmission is smooth, offering a reliable, novel, and multifunctional technical improvement for hub motors in heavy-duty electric vehicles.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] The present invention relates to a three-speed hub motor powertrain with high torque, characterized in that: the three-speed hub motor is composed of a gear transmission module, a shifting module, and a power module; the three-speed hub motor with three brakes includes parts such as a motor shaft, bearing end caps, motor stator, left sun gear, left planet gear, left planet carrier, gear ring, hub, right first planet gear, right second planet gear, right third planet gear, right planet carrier, right sun gear, sealing ring, housing, motor rotor, first brake, second brake, third brake, first brake oil circuit, second brake oil circuit, and third brake oil circuit.

[0011] The gear transmission module includes a motor shaft, a left sun gear, a left planet gear, a left planet carrier, a gear ring, a right first planet gear, a right second planet gear, a right third planet gear, a right planet carrier, and a right sun gear. The left end of the motor shaft forms a rotating pair with the housing and is fitted with a bearing, with a bearing end cap engaging with it. Simultaneously, the right end forms a rotating pair with the right planet carrier and is fitted with a bearing. The left sun gear meshes externally with the left planet gear and is connected to the motor rotor via a key. The left planet gear meshes internally with the gear ring and forms a rotating pair with the left planet carrier, with a bearing between them. The right sun gear meshes with the... The first planetary gear on the right side is externally meshed and connected to the motor shaft via a key, closely abutting the shoulder of the motor shaft to complete axial positioning; the first planetary gear on the right side is externally meshed with the second planetary gear on the right side, forming a rotating pair with the right planetary carrier and a bearing is installed between them; the second planetary gear on the right side is externally meshed with the third planetary gear on the right side, forming a rotating pair with the right planetary carrier and a bearing is installed between them; the third planetary gear on the right side is internally meshed with the gear ring, forming a rotating pair with the right planetary carrier and a bearing is installed between them; the right planetary carrier is fixed to the hub with screws, forming a rotating pair with the outer casing and equipped with a sealing ring.

[0012] The shifting module includes a first brake, a second brake, a third brake, a first brake oil circuit, a second brake oil circuit, and a third brake oil circuit. The gear ring of the first brake is fixedly connected to the outer side of the gear ring, and the outer ring of the first brake is fixedly connected to the housing. The gear ring of the second brake is fixedly connected to the left planetary carrier, and the outer ring of the second brake is fixedly connected to the housing. The gear ring of the third brake is fixedly connected to the motor shaft, and the outer ring of the third brake is fixedly connected to the inwardly extending portion of the gear ring. The first brake oil circuit is located inside the motor shaft and simultaneously provides hydraulic oil to the first brake. The second brake oil circuit is located inside the motor shaft and simultaneously provides hydraulic oil to the second brake. The third brake oil circuit is located inside the motor shaft and simultaneously provides hydraulic oil to the third brake.

[0013] The power module includes a motor stator and a motor rotor; the motor stator is fixedly connected to the housing; the motor rotor is fixedly connected to the motor shaft and is also connected to the left sun gear via a key.

[0014] The first brake oil circuit, the second brake oil circuit, and the third brake oil circuit are hidden in the motor shaft and housing, so there is no need to arrange oil circuits separately.

[0015] The motor stator is in close contact with the housing to facilitate heat dissipation.

[0016] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0017] 1. This invention employs a layout of one motor, two planetary gear sets, and three brakes, offering advantages such as convenient gear shifting and reliable safety. The three brakes work together to achieve flexible switching between neutral, parking, and three-speed driving gears, and can output different levels of torque, adapting to the complex road conditions encountered by heavy-duty electric vehicles.

[0018] 2. This invention employs a wet multi-disc brake for gear shifting control, utilizing a hydraulic control scheme. This design offers advantages such as safety, reliability, high braking force, and lightweight operation. The hydraulic circuit is concealed within the hub motor housing and motor shaft, saving space. Different brakes work together to achieve gear switching.

[0019] 3. This invention employs an unconventional planetary gear train, with helical gears as the planetary gears. The line connecting the center points of the planetary gears is not a straight line and does not pass through the center point of the sun gear, which greatly reduces the volume of the planetary gear train and shortens the length of the planet carrier, increasing its resistance to bending moments. The planetary gear train has advantages such as small lateral space occupation, high load-bearing capacity, and good stability, and can meet the design requirements of different driving conditions, exhibiting strong adaptability.

[0020] 4. The present invention adopts a structure in which the motor stator is in close contact with the housing, and the motor stator is far away from the center of the power assembly, which greatly improves its heat dissipation performance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is the transmission route diagram for gear D1 of the present invention;

[0023] Figure 3 This is the transmission route diagram for gear D2 of the present invention;

[0024] Figure 4 This is the transmission route diagram for gear D3 of the present invention;

[0025] Figure 5 This is a cross-sectional view of the oil circuit of the present invention;

[0026] Figure 6 This is a layout diagram of the planetary gear system on the right side of the present invention;

[0027] The components include: 1. Motor shaft, 2. Bearing end cover, 3. Motor stator, 4. Left sun gear, 5. Left planet gear, 6. Left planet carrier, 7. Gear ring, 8. Hub, 9. Right first planet gear, 10. Right second planet gear, 11. Right third planet gear, 12. Right planet carrier, 13. Right sun gear, 14. Sealing ring, 15. Housing, 16. Motor rotor, B1. First brake, B2. Second brake, B3. Third brake, W1. First brake oil circuit, W2. Second brake oil circuit, W3. Third brake oil circuit. Detailed Implementation

[0028] The following description, in conjunction with the accompanying drawings, provides a further illustration of the present invention's three-speed variable-speed hub motor powertrain with high torque through examples.

[0029] like Figure 1 The main features of this invention include a motor shaft 1, a bearing end cover 2, a motor stator 3, a left sun gear 4, a left planet gear 5, a left planet carrier 6, a gear ring 7, a hub 8, a right first planet gear 9, a right second planet gear 10, a right third planet gear 11, a right planet carrier 12, a right sun gear 13, a sealing ring 14, a housing 15, a motor rotor 16, a first brake B1, a second brake B2, a third brake B3, a first brake oil circuit W1, a second brake oil circuit W2, and a third brake oil circuit W3.

[0030] The gear transmission module includes a motor shaft 1, a left sun gear 4, a left planet gear 5, a left planet carrier 6, a ring gear 7, a right first planet gear 9, a right second planet gear 10, a right third planet gear 11, a right planet carrier 12, and a right sun gear 13. The left end of the motor shaft 1 forms a rotating pair with the housing 15 and is fitted with a bearing, with a bearing end cap 2 cooperating with it. Simultaneously, the right end forms a rotating pair with the right planet carrier 12 and is fitted with a bearing. The left sun gear 4 externally meshes with the left planet gear 5 and is connected to the motor rotor 16 via a key. The left planet gear 5 internally meshes with the ring gear 7 and forms a rotating pair with the left planet carrier 6, with a bearing installed between them. The right sun gear 13 and... The first planetary gear 11 on the right side is externally engaged and connected to the motor shaft 1 by a key, and closely abuts against the shoulder of the motor shaft 1 to complete axial positioning; the first planetary gear 11 on the right side is externally engaged with the second planetary gear 10 on the right side, and forms a rotating pair with the planetary carrier 12 on the right side, with a bearing installed between them; the second planetary gear 10 on the right side is externally engaged with the third planetary gear 9 on the right side, and forms a rotating pair with the planetary carrier 12 on the right side, with a bearing installed between them; the third planetary gear 9 on the right side is internally engaged with the gear ring 8, and forms a rotating pair with the planetary carrier 12 on the right side, with a bearing installed between them; the planetary carrier 12 on the right side is fixed to the hub 8 by screws, and forms a rotating pair with the outer casing 15, with a sealing ring 14 installed. The shifting module includes a first brake B1, a second brake B2, a third brake B3, a first brake oil circuit W1, a second brake oil circuit W2, and a third brake oil circuit W3; the gear ring of the first brake B1 is fixedly connected to the outer side of the gear ring 7, and the outer ring of the first brake B1 is fixedly connected to the housing 15; the gear ring of the second brake B2 is fixedly connected to the left planetary carrier 6, and the outer ring of the second brake B2 is fixedly connected to the housing 15; the gear ring of the third brake B3 is fixedly connected to the motor shaft 1, and the outer ring of the third brake B3 is fixedly connected to the inwardly extending portion of the gear ring 7; The first brake oil circuit W1 is located inside the motor shaft 1 and provides hydraulic oil to the first brake B1; the second brake oil circuit W2 is located inside the motor shaft 1 and provides hydraulic oil to the second brake B2; the third brake oil circuit W3 is located inside the motor shaft 1 and provides hydraulic oil to the third brake B3; the power module includes a motor stator 3 and a motor rotor 16; the motor stator 3 is fixedly connected to the housing 15; the motor rotor 16 is fixedly connected to the motor shaft 1 and is also connected to the left sun gear 4 via a key.

[0031] like Figure 5 The invention is characterized by integrating the oil circuits of the three brakes inside the motor shaft 1 and the housing. The three oil circuits do not interfere with each other. The W1 oil circuit supplies oil to the first brake B1, the W2 oil circuit supplies oil to the second brake B2, and the W3 oil circuit supplies oil to the third brake B3.

[0032] like Figure 6 The invention is characterized by the use of an unconventional planetary gear train. Figures 1-4 The left planetary gear train has a staggered arrangement of the ring gear 7, the right first planetary gear 9, the right second planetary gear 10, the right third planetary gear 11, and the right sun gear 13, which greatly reduces the longitudinal dimension of the planetary gear train. Furthermore, due to the shortening of the planet carrier, its bending moment resistance is significantly improved.

[0033] The working principle of this invention is explained as follows:

[0034] Based on the existing speed requirements of electric vehicles and considering the shifting requirements of electric vehicles under special road conditions, the number of gear teeth is designed as shown in Table 1.

[0035] Table 1 Gear Tooth Count Table

[0036]

[0037] like Figure 1 As shown in the figure, the shifting module of a three-speed hub motor powertrain with high torque in this embodiment uses three brakes. The actuators for each gear are shown in Table 2.

[0038] Table 2 Working Table of Shift Actuating Elements

[0039]

[0040] Note: In the table, "●" indicates combination, and "○" indicates separation;

[0041] Combination Figure 1 , Figure 2 And Table 2, the transmission routes for each item are explained as follows:

[0042] (1) Parking gear (P gear)

[0043] like Figure 1 As shown, when the inner and outer friction pads of the first brake B1, the second brake B2, and the third brake B3 are all engaged, the entire wheel system is locked, the tires will not be able to rotate, and the vehicle will be parked.

[0044] (2) Neutral (N gear)

[0045] like Figure 1 As shown, when the inner and outer friction pads of the first brake B1, the second brake B2, and the third brake B3 are all separated, the two planetary gear trains become two differential gear trains, the wheels are not controlled by the driving force, and they enter the neutral state.

[0046] (3) Move forward one gear (D1 gear)

[0047] Figure 2As shown, when the inner and outer friction pads of the first brake B1 remain engaged, and the second brake B2 and the third brake B3 remain disengaged, the left planetary carrier 6 remains stationary relative to the outer casing 15. At this time, both the left and right planetary gear trains participate in power output. The main function of the left planetary gear train is to transmit the power from the motor stator 3 and motor rotor 16 to the ring gear 7 via the left sun gear 4 and left planet gears 5. The main function of the right planetary gear train is to combine the power transmitted from the left planetary gear train to the ring gear 7, and transmit the power directly transmitted from the motor stator 3 and motor rotor 16 via the motor shaft 1, right sun gear 13, right first planet gear 11, right second planet gear 10, and right third planet gear 9 to the right planetary carrier 12, and then output the power to the wheel hub 8, driving the car forward at a gear ratio of 10.

[0048] (4) Move forward to second gear (D2 gear)

[0049] Figure 3 As shown, when the inner and outer friction pads of the second brake B2 remain engaged, and the first brake B1 and the third brake B3 remain disengaged, the gear ring 7 remains stationary relative to the housing 15. At this time, only the right planetary gear train participates in power transmission. The left sun gear 4, left planet gear 5, and left planet carrier 6 are idle and do not participate in power transmission. The motor stator 3 and motor rotor 16 output power to the motor shaft 1, and then transmit the power to the right planet carrier 12 through the right sun gear 13, right first planet gear 11, right second planet gear 10, and right third planet gear 9, and then output the power to the wheel hub 8, driving the car forward at a transmission ratio of 3.

[0050] (5) Move forward to third gear (D3 gear)

[0051] Figure 4 As shown, when the inner and outer friction plates of the third brake B3 remain engaged, and the first brake B1 and the second brake B2 remain disengaged, the gear ring 7 remains relatively stationary with the motor shaft 1. The planetary gear train can then be considered a single, stationary unit. The left sun gear 4, left planet gear 5, left planet carrier 6, right first planet gear 11, right second planet gear 10, right third planet gear 9, and right sun gear 13 remain relatively stationary with the outer casing 15. The power generated by the motor stator 3 and motor rotor 16 is directly output to the right planet carrier 12, and then to the wheel hub 8, driving the car forward at a transmission ratio of 1.

Claims

1. A three-gear variable speed wheel hub motor power assembly with large torque, characterized in that: The three-gear variable speed wheel hub motor is composed of a gear transmission module, a gear shifting module and a power module; the three-gear wheel hub motor with three brakes comprises a motor shaft (1), a bearing end cover (2), a motor stator (3), a left sun gear (4), a left planetary gear (5), a left planetary carrier (6), a gear ring, a wheel hub, a right first planetary gear, a right second planetary gear (10), a right third planetary gear, a right planetary carrier (12), a right sun gear (13), a sealing ring (14), an outer shell (15), a motor rotor (16), a first brake (B1), a second brake (B2), a third brake (B3), a first brake oil way (W1), a second brake oil way (W2) and a third brake oil way (W3); the gear transmission module comprises the motor shaft (1), the left sun gear (4), the left planetary gear (5), the left planetary carrier (6), the gear ring, the right first planetary gear, the right second planetary gear (10), the right third planetary gear, the right planetary carrier (12) and the right sun gear (13); the left end of the motor shaft (1) forms a rotary pair with the outer shell (15) and is provided with a bearing, and the bearing end cover (2) is matched with the rotary pair; the right end of the motor shaft (1) forms a rotary pair with the right planetary carrier (12) and is provided with a bearing; the left sun gear (4) is externally meshed with the left planetary gear (5), and is connected with the motor rotor (16) through a key; the left planetary gear (5) is internally meshed with the gear ring, forms a rotary pair with the left planetary carrier (6) and is provided with a bearing therebetween; the right sun gear (13) is externally meshed with the right first planetary gear, is connected with the motor shaft (1) through a key and is closely adjacent to the shaft shoulder of the motor shaft (1), thereby completing axial positioning; the right first planetary gear is externally meshed with the right second planetary gear (10), forms a rotary pair with the right planetary carrier (12) and is provided with a bearing therebetween; the right second planetary gear (10) is externally meshed with the right third planetary gear, forms a rotary pair with the right planetary carrier (12) and is provided with a bearing therebetween; the right third planetary gear is internally meshed with the gear ring, forms a rotary pair with the right planetary carrier (12) and is provided with a bearing therebetween; the right planetary carrier (12) is fixedly connected with the wheel hub through a screw, forms a rotary pair with the outer shell (15) and is provided with the sealing ring (14) therebetween; the gear shifting module comprises the first brake (B1), the second brake (B2), the third brake (B3), the first brake oil way (W1), the second brake oil way (W2) and the third brake oil way (W3); the gear ring of the first brake (B1) is fixedly connected with the outside of the gear ring, and the outer ring of the first brake (B1) is fixedly connected with the outer shell (15); the gear ring of the second brake (B2) is fixedly connected with the left planetary carrier (6), and the outer ring of the second brake (B2) is fixedly connected with the outer shell (15); the gear ring of the third brake (B3) is fixedly connected with the motor shaft (1), and the outer ring of the third brake (B3) is fixedly connected with the inwardly extended part of the gear ring.The first brake oil way (W1) is located inside the motor shaft (1), and provides hydraulic oil for the first brake (B1); the second brake oil way (W2) is located inside the motor shaft (1), and provides hydraulic oil for the second brake (B2); the third brake oil way (W3) is located inside the motor shaft (1), and provides hydraulic oil for the third brake (B3).

2. The three-gear variable speed wheel hub motor power assembly with large torque according to claim 1, characterized in that: The power module comprises a motor stator (3) and a motor rotor (16); the motor stator (3) is fixedly connected with the shell (15); the motor rotor (16) is fixedly connected with the motor shaft (1) and is connected with the left sun gear (4) through a key.

3. The three-gear variable speed wheel hub motor power assembly with large torque according to claim 1, characterized in that: The first brake oil path (W1), the second brake oil path (W2) and the third brake oil path (W3) are hidden in the motor shaft (1) and the shell (15), and no additional oil path is arranged.

4. The three-gear variable speed wheel hub motor power assembly with large torque according to claim 1, characterized in that: The motor stator (3) is in close contact with the shell (15), is farthest away from the structural center, and is convenient for heat dissipation.

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