Hub drive system

Abstract

A hub drive system includes a housing (10), a motor (E), two planetary gear sets, and a hub bearing (B1). The hub bearing (B1) includes a central shaft (B11) and an outer ring (B13). The central shaft (B11) is fixed relative to the housing (10). A first-stage sun gear (GS1) and a second-stage sun gear (GS2) are both sleeved on the outer periphery of the hub bearing (B1). The stator (ES), the first-stage ring gear (GR1), and the second-stage ring gear (GR2) of the motor (E) are all fixed to the housing (10). The rotor (ER) of the motor (E) is torsionally connected to the first-stage sun gear (GS1), the first-stage planetary carrier (GC1) is torsionally connected to the second-stage sun gear (GS2), and the second-stage planetary carrier (GC2) is torsionally connected to the outer ring (B13). The outer ring (B13) is used to torsionally connect to the wheel rim, thereby enabling the power of the motor (E) to be transmitted to the wheel rim.

Description

Technical Field

[0001] This invention relates to the field of vehicles, and particularly to a hub drive system for new energy vehicles using hub drive. Background Technology

[0002] For electric vehicles, especially heavy-duty vehicles, the drive methods can be divided into central motor drive and wheel hub motor drive.

[0003] For vehicles driven by a central motor, the drive system includes a central drive motor, a clutch, and a reducer that can provide two or three gear ratios. Such a drive system contains many transmission components, has a long transmission chain, and is heavy, which leads to significant energy loss and low transmission efficiency during power transmission.

[0004] For vehicles using in-wheel motors, especially heavy-duty vehicles, the drive and braking components are typically located inside the wheel rim. The drive component includes the drive motor, a planetary gear reducer (usually with a two-stage planetary gear set), and wheel hub bearings.

[0005] For example, Chinese patent CN106864251B and Chinese patent publications CN107128162A and CN109866607A disclose a type of hub drive system using a differential planetary gear reducer. In this type of hub drive system, the two planetary gear sets of the reducer are differential, or the ring gears of the two planetary gear sets are shared. Therefore, the gears involved in the transmission need to be coupled. Such planetary gear reducers are difficult to design and manufacture modularly, and the assembly of components is complex.

[0006] For example, Chinese patent publications CN103328247A, CN103026103A, and CN102648362A disclose a type of hub drive system using a cycloidal gear reducer. However, cycloidal gears have complex manufacturing processes, low transmission efficiency, and high costs. Summary of the Invention

[0007] The purpose of this invention is to overcome or at least mitigate the shortcomings of the prior art and provide a hub drive system with a simple structure and a large transmission ratio.

[0008] This invention provides a hub drive system, comprising a housing, a motor, two planetary gear sets, and a hub bearing. The first planetary gear set includes a first-stage sun gear, a first-stage planet carrier, and a first-stage ring gear; the second planetary gear set includes a second-stage sun gear, a second-stage planet carrier, and a second-stage ring gear. The hub bearing includes a central shaft, rolling elements, and an outer ring. The central shaft is fixed relative to the housing.

[0009] Both the primary sun gear and the secondary sun gear are fitted onto the outer circumference of the hub bearing.

[0010] The stator, primary gear ring, and secondary gear ring of the motor are all fixed to the housing. The rotor of the motor is connected to the primary sun gear in a non-rotational manner, the primary planetary carrier is connected to the secondary sun gear in a non-rotational manner, and the secondary planetary carrier is connected to the outer ring in a non-rotational manner.

[0011] The outer ring is used to connect to the rim in a way that prevents relative rotation, thereby enabling the power of the motor to be transmitted to the rim.

[0012] In at least one embodiment, the axial length of the central shaft is greater than the axial length of the outer ring, the central shaft passes through the housing, the outer ring is disposed at a first end of the central shaft, and the second end of the central shaft is not covered by the outer ring.

[0013] In at least one embodiment, one axial end of the outer ring has a flange portion that protrudes radially outward from the outer ring, the flange portion being used to connect to the rim.

[0014] In at least one embodiment, in the axial direction, the first-stage sun gear is partially fitted around the outer periphery of the outer ring and partially fitted around the outer periphery of the area of ​​the central shaft not covered by the outer ring, and the second-stage sun gear is fitted around the outer periphery of the outer ring.

[0015] In at least one embodiment, the hub drive system further includes a braking device that is partially connected to the first-stage sun gear in a non-rotatable manner, thereby enabling the transmission of braking torque to the first-stage sun gear during braking operations.

[0016] In at least one embodiment, the braking device is a drum brake, comprising a brake drum and brake pads. The brake drum is non-rotatably connected to the primary sun gear, and the brake pads are connected to the housing.

[0017] In the non-braking state, the brake pads do not contact the brake drum; in the braking state, the brake pads press against the inner peripheral wall of the brake drum.

[0018] In at least one embodiment, the inner cavity of the housing has an annular first partition wall and a second partition wall connected to the inner peripheral wall of the housing and spaced apart axially in the housing. The first partition wall and the second partition wall divide the inner cavity of the housing into three chambers axially, namely a brake chamber, a motor chamber, and a gear chamber.

[0019] The braking device is located in the braking chamber.

[0020] The motor is located in the motor room.

[0021] The primary planetary carrier, the primary ring gear, the secondary sun gear, the secondary planetary carrier, and the secondary ring gear are located in the gear chamber.

[0022] The primary sun gear extends from the gear chamber through the motor chamber to the brake chamber.

[0023] In at least one embodiment, the housing includes an intermediate housing, a first cover, a second cover, and a support plate.

[0024] The intermediate shell is cylindrical, with open openings at both ends in the axial direction. The second partition wall is located on the inner circumference of the intermediate shell.

[0025] The first cover and the second cover are respectively installed at two ends of the intermediate housing.

[0026] The first partition wall is located on the inner periphery of the first cover.

[0027] The support plate is mounted on the end of the first cover that is axially away from the first partition wall.

[0028] In the axial direction, the region between the first cover and the first partition wall forms the brake chamber, the region between the first partition wall and the second partition wall forms the motor chamber, and the region between the second partition wall and the second cover forms the gear chamber.

[0029] In at least one embodiment, a first bearing is provided between the first partition wall and the first-stage sun gear, and a second bearing is provided between the second partition wall and the first-stage sun gear.

[0030] In at least one embodiment, an annular first seal is provided between the second partition wall and the first-stage sun gear, the first seal being located axially on the side of the second bearing closer to the first partition wall.

[0031] A second annular seal is provided between the hub bearing and the first-stage sun gear, and the second seal is located axially at the end of the outer ring near the first partition wall.

[0032] In at least one embodiment, an annular third seal is provided between the flange and the housing.

[0033] In at least one embodiment, a third bearing is provided between the secondary sun gear and the outer ring.

[0034] In at least one embodiment, a thrust bearing is provided between the primary planetary carrier and the secondary planetary carrier.

[0035] In at least one embodiment, the second partition wall is partially formed in a stepped shape such that the second partition wall includes an annular stepped portion, the stepped portion including a stepped peripheral wall and a stepped end wall.

[0036] The outer peripheral wall of the primary gear ring is connected to the stepped peripheral wall with an interference fit, and one end of the primary gear ring abuts against the stepped end wall.

[0037] In at least one embodiment, an elastic retaining ring is provided at the other end of the primary gear ring, the elastic retaining ring preventing the primary gear ring from disengaging from the stepped portion.

[0038] The inner circumferential side of the stepped peripheral wall is provided with an annular groove, and the elastic retaining ring is disposed in the annular groove.

[0039] The hub drive system according to the present invention has a simple structure, a high degree of modularity, and can provide a large transmission ratio. Attached Figure Description

[0040] Figure 1 A cross-sectional view of a hub drive system according to an embodiment of the present invention is shown.

[0041] Explanation of reference numerals in the attached figures:

[0042] 10. Shell; 11. Intermediate shell; 12. First cover; 13. Second cover; 14. Support plate;

[0043] W1 First partition wall; W2 Second partition wall; Ws Staircase section; Ws1 Staircase perimeter wall; Ws2 Staircase end wall;

[0044] 20 Braking device; 21 Brake drum; 22 Brake pad;

[0045] 30 Cooling jacket; 31 Cooling interface; 40 Flexible retaining ring;

[0046] E-motor; ES stator; ER rotor; F rotor bracket;

[0047] GS1 primary sun gear; GR1 primary ring gear; GC1 primary planetary carrier;

[0048] GS2 secondary sun gear; GR2 secondary ring gear; GC2 secondary planetary carrier;

[0049] B1 hub bearing; B11 center axle; B12 rolling element; B13 outer ring; B13f flange;

[0050] B21 First bearing; B22 Second bearing; B23 Third bearing; B24 Thrust bearing;

[0051] R1 Brake chamber; R2 Motor chamber; R3 Gear chamber;

[0052] S1 First seal; S2 Second seal; S3 Third seal; Sn sensor. Detailed Implementation

[0053] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are for teaching those skilled in the art how to implement the present invention, and are not intended to exhaustively describe all possible ways of the invention, nor to limit the scope of the invention.

[0054] Unless otherwise specified, refer to Figure 1 A represents the axial direction of the hub drive system, which is consistent with the axial direction of the motor E in the hub drive system; R represents the radial direction of the hub drive system, which is consistent with the radial direction of the motor E in the hub drive system.

[0055] The hub drive system according to the present invention mainly includes a housing 10, a motor E, a rotor support F, a two-stage planetary gear set, a hub bearing B1, and a braking device 20.

[0056] The first planetary gear set includes a first-stage sun gear GS1, a first-stage ring gear GR1, a first-stage planet carrier GC1, and first-stage planet gears. The second planetary gear set includes a second-stage sun gear GS2, a second-stage ring gear GR2, a second-stage planet carrier GC2, and second-stage planet gears.

[0057] The hub bearing B1 includes a central shaft B11, rolling elements B12, and an outer ring B13. The central shaft B11 is shaft-shaped and passes through the housing 10. The outer ring B13 is fitted around the outer circumference of the central shaft B11. The axial length of the outer ring B13 is less than the axial length of the central shaft B11. The outer ring B13 is positioned near one end of the housing 10 in the axial direction A, or in other words, it is positioned near one end of the central shaft B11. The end of the central shaft B11 covered by the outer ring B13 is the first end, and the other end of the central shaft B11 is the second end.

[0058] The central shaft B11 is fixedly disposed relative to the housing 10. Specifically, the second end of the central shaft B11 is fixed to the support plate 14 of the housing 10, which will be described below. The outer ring B13 is rotatable relative to the central shaft B11.

[0059] In this embodiment, the braking device 20 is a drum braking device, which includes a brake drum 21 and a brake pad 22.

[0060] The motor E, hub bearing B1, first-stage sun gear GS1, first-stage ring gear GR1, first-stage planetary carrier GC1, second-stage sun gear GS2, second-stage ring gear GR2, second-stage planetary carrier GC2, and drum-shaped brake device 20 are all coaxially arranged.

[0061] The stator ES of motor E is fixed to housing 10, and the rotor ER of motor E is located on the inner circumference of stator ES. Preferably, a cooling sleeve 30 is provided between stator ES and housing 10, and a cooling cavity is formed between cooling sleeve 30 and inner wall of housing 10, and cooling interface 31 communicating with cooling cavity is provided on housing 10.

[0062] The rotor support F is roughly annular and is torsionally (without relative rotation) connected to the rotor ER. The rotor support F is used to transmit the torque of the rotor ER to the planetary gear set.

[0063] The primary sun gear GS1 is fitted onto the outer circumference of the hub bearing B1 and the inner circumference of the rotor support F. Axially, the primary sun gear GS1 is partially fitted onto the outer circumference of the outer ring B13 and partially fitted onto the outer circumference of the central shaft B11 in the area not covered by the outer ring B13. The primary sun gear GS1 is torsionally connected to the rotor support F.

[0064] Preferably, to provide good radial support for the primary sun gear GS1, the housing 10 also includes a first bearing B21 and a second bearing B22. The outer rings of the first bearing B21 and the second bearing B22 are torsionally connected to the housing 10, and the inner rings of the first bearing B21 and the second bearing B22 are torsionally connected to the primary sun gear GS1. The first bearing B21 and the second bearing B22 are located on opposite sides of the connection area between the rotor support F and the primary sun gear GS1 in the axial direction A.

[0065] Specifically, in order to facilitate the installation of the first bearing B21 and the second bearing B22, and also to relatively isolate the motor E from other components, the inner cavity of the housing 10 forms two annular partitions (these two partitions, namely the first partition W1 and the second partition W2, will be further described below).

[0066] In this embodiment, the housing 10 is divided into an intermediate housing 11, a first cover 12, a second cover 13, and a support plate 14.

[0067] The intermediate shell 11 is cylindrical, with open openings at both ends along the axial direction A.

[0068] The first cover 12, the second cover 13, and the support plate 14 are all annular with an opening in the middle.

[0069] The first cover 12 and the second cover 13 are respectively fixed to the openings at both ends of the intermediate housing 11 by screws.

[0070] The inner periphery of the first cover 12 forms a first partition wall W1, and the axial center of the inner cavity of the intermediate shell 11 forms a second partition wall W2.

[0071] The first partition wall W1 is recessed toward the second partition wall W2 in the axial direction A, such that a cavity is formed between the axial end of the first cover 12 away from the second cover 13 and the first partition wall W1, which is used to accommodate the braking device 20, which will be further described below, and is referred to as the braking chamber R1 below.

[0072] The support plate 14 is fixed, for example, to the axial end of the first cover 12 away from the second cover 13 by screws; therefore, it is also said that a brake chamber R1 is formed between the support plate 14 and the first partition wall W1. As described above, the support plate 14 serves to support the central axle B11. Furthermore, the brake actuator and brake pads 22 of the brake device 20, which will be described below, are also mounted on the support plate 14. The support plate 14 can be connected to the vehicle's suspension.

[0073] The second partition wall W2 divides the inner cavity of the intermediate housing 11 into two chambers along the axial direction A: a motor chamber R2 near the first partition wall W1 (or, in other words, the motor chamber R2 is located between the first partition wall W1 and the second partition wall W2) and a gear chamber R3 near the second cover 13 (or, in other words, the gear chamber R3 is located between the second partition wall W2 and the second cover 13).

[0074] The motor E is housed in the motor chamber R2. Except for the first-stage sun gear GS1, the two planetary gear sets are housed in the gear chamber R3. The first-stage sun gear GS1 extends from the gear chamber R3 through the motor chamber R2 to the brake chamber R1.

[0075] The second partition wall W2 is stepped. The stepped part Ws of the second partition wall W2 is used to fix the first-stage gear ring GR1, which will be introduced below. At the same time, the stepped shape also allows the second partition wall W2 to adapt to the shape of the various components contained in the housing 10.

[0076] The first bearing B21 mentioned above is disposed on the inner circumference of the first partition wall W1, and the outer ring of the first bearing B21 is connected to the first partition wall W1 with an interference fit; the second bearing B22 is disposed on the inner circumference of the second partition wall W2, and the outer ring of the second bearing B22 is connected to the second partition wall W2 with an interference fit.

[0077] Preferably, a sensor Sn for measuring the rotational speed of motor E is provided between the first partition wall W1 and the rotor support F. The sensor Sn is, for example, a rotary transformer. The stator of the sensor Sn is mounted on the first partition wall W1, and the rotor of the sensor Sn is mounted on the rotor support F.

[0078] The primary gear ring GR1 is fixed to the housing 10. Specifically, the primary gear ring GR1 is fixed to the stepped portion Ws of the second partition wall W2. The stepped portion Ws includes a stepped peripheral wall Ws1 and a stepped end wall Ws2. The outer peripheral wall of the primary gear ring GR1 is interference-fitted with the stepped peripheral wall Ws1, and one end of the primary gear ring GR1 abuts against the stepped end wall Ws2.

[0079] The primary planetary carrier GC1 is connected to the secondary sun gear GS2 in an anti-torsional manner.

[0080] The secondary sun gear GS2 is fitted onto the outer ring B13, and the secondary sun gear GS2 and the outer ring B13 can rotate relative to each other. Preferably, a third bearing B23 is provided between the secondary sun gear GS2 and the outer ring B13. More preferably, the third bearing B23 is a needle roller bearing.

[0081] The secondary gear ring GR2 is fixed to the housing 10. Specifically, the secondary gear ring GR2 is torsionally connected to the inner peripheral wall of the intermediate housing 11.

[0082] The secondary planetary carrier GC2 is torsionally connected to the outer ring B13 of the hub bearing B1. Specifically, the outer ring B13 has a flange portion B13f that protrudes outward in the radial direction R near the second cover 13 in the axial direction A, and the secondary planetary carrier GC2 is connected to the flange portion B13f.

[0083] The flange B13f is torsionally connected to the rim (not shown) by means of, for example, bolts, thereby transmitting the driving torque to the rim.

[0084] Preferably, an elastic retaining ring 40 is provided on the side of the first-stage gear ring GR1 near the second cover 13 in the axial direction A. The elastic retaining ring 40 is fixed in the annular groove formed by the inner wall of the intermediate housing 11. The elastic retaining ring 40 can limit the first-stage gear ring GR1 in the axial direction A and prevent the first-stage gear ring GR1 from disengaging from the stepped part Ws.

[0085] Preferably, a thrust bearing B24 is provided between the first-stage planetary carrier GC1 and the second-stage planetary carrier GC2. On the one hand, the thrust bearing B24 avoids direct contact between the first-stage planetary carrier GC1 and the second-stage planetary carrier GC2, which rotate at different speeds; on the other hand, when the planetary gear set uses helical gears, the planetary carriers will bear axial forces, and at this time, the thrust bearing B24 plays the role of supporting the two planetary carriers in the axial direction A.

[0086] Preferably, an annular first seal S1 is provided between the second partition wall W2 and the first-stage sun gear GS1, and the first seal S1 is located on the side of the second bearing B22 near the first partition wall W1 in the axial direction A; an annular second seal S2 is provided between the hub bearing B1 and the first-stage sun gear GS1, and the second seal S2 is located on the end of the outer ring B13 near the first partition wall W1 in the axial direction A; an annular third seal S3 is provided between the flange portion B13f of the outer ring B13 and the second cover 13. The above three seals seal and isolate the gear chamber R3 from the surrounding space, which can prevent lubricant from leaking from the gear chamber R3 and prevent contaminants from entering the gear chamber R3.

[0087] The braking device 20 is located inside the brake chamber R1. The brake drum 21 is torsionally connected to the first-stage sun gear GS1, and the brake pads 22 are connected to the support plate 14. When braking is applied, the brake pads 22 are pressed against the inner wall of the brake drum 21, and friction is generated between the brake pads 22 and the brake drum 21, thereby slowing down or even stopping the rotation of the brake drum 21.

[0088] The following describes the torque (or power) transmission path of the hub drive system according to the present invention during transmission and braking, wherein the braking of the hub drive system includes braking of the motor E itself and mechanical braking using the braking device 20.

[0089] (i) Power transmission path for motor E to drive

[0090] During the rotation of the wheel rim driven by motor E, the transmission path of the rotational torque is as follows: rotor ER, rotor support F, first-stage sun gear GS1, first-stage planetary gear, first-stage planetary carrier GC1, second-stage sun gear GS2, second-stage planetary gear, second-stage planetary carrier GC2, outer ring B13 to the wheel rim.

[0091] (ii) Power transmission path for motor E to apply braking

[0092] When motor E applies braking, the transmission path of braking torque is as follows: rotor ER, rotor support F, first-stage sun gear GS1, first-stage planetary gear, first-stage planetary carrier GC1, second-stage sun gear GS2, second-stage planetary gear, second-stage planetary carrier GC2, outer ring B13 to rim.

[0093] (iii) Power transmission path for braking by braking device 20

[0094] When the braking device 20 applies braking, the transmission path of the braking torque is as follows: brake drum 21, first-stage sun gear GS1, first-stage planetary gear, first-stage planetary carrier GC1, second-stage sun gear GS2, second-stage planetary gear, second-stage planetary carrier GC2, outer ring B13 to rim.

[0095] The following is a brief description of some of the beneficial effects of the above-described embodiments of the present invention.

[0096] (i) The hub drive system according to the present invention has a simple structure, a short transmission chain, and high transmission efficiency.

[0097] (ii) This invention uses a two-stage planetary gear set, which can achieve a large transmission ratio. The two planetary gear sets are connected in series, and the size and structure design of each planetary gear set can be carried out independently, representing a decoupled design. When different applications require different speed ratios, the design can be adjusted by changing the size and structure of only one planetary gear set. Compared to differentially connected planetary gear sets, the planetary gear set according to this invention is easier to modularize.

[0098] (iii) The braking device 20 of the present invention is torsionally connected to the input end of the planetary gear set (i.e., the first-stage sun gear GS1), and the braking torque of the braking device 20 can be amplified by the planetary gear set. Compared with common methods such as directly connecting the braking device to the wheel, the braking device 20 of the wheel hub drive system according to the present invention only requires a smaller braking torque to meet the braking requirements of the vehicle, thus reducing the size and weight of the braking device.

[0099] (iv) The inner cavity of the housing 10 forms a first partition wall W1 and a second partition wall W2, which not only facilitates the connection and positioning of various components, but also divides the inner cavity of the housing 10 into three chambers, making it difficult for the heat generated during the rotation of the motor E and the heat generated during the braking of the braking device 20 to be transferred to other components.

[0100] It should be understood that the above embodiments are merely exemplary and are not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the above embodiments under the guidance of the present invention without departing from the scope of the present invention.

Claims

1. A hub drive system comprising a housing (10), a motor (E), two planetary gear sets, and a hub bearing (B1), wherein the first planetary gear set comprises a first-stage sun gear (GS1), a first-stage planetary carrier (GC1), and a first-stage ring gear (GR1), and the second planetary gear set comprises a second-stage sun gear (GS2), a second-stage planetary carrier (GC2), and a second-stage ring gear (GR2), and the hub bearing (B1) comprises a central shaft (B11), rolling elements (B12), and an outer ring (B13), wherein the central shaft (B11) is fixed relative to the housing (10), wherein, Both the primary sun gear (GS1) and the secondary sun gear (GS2) are fitted onto the outer circumference of the hub bearing (B1). The stator (ES), the first-stage ring gear (GR1), and the second-stage ring gear (GR2) of the motor (E) are all fixed to the housing (10). The rotor (ER) of the motor (E) is connected to the first-stage sun gear (GS1) in a non-rotational manner, the first-stage planetary carrier (GC1) is connected to the second-stage sun gear (GS2) in a non-rotational manner, and the second-stage planetary carrier (GC2) is connected to the outer ring (B13) in a non-rotational manner. The outer ring (B13) is used to connect to the rim in a way that prevents relative rotation, thereby enabling the power of the motor (E) to be transmitted to the rim; Wherein, the length of the central shaft (B11) in the axial direction (A) is greater than the length of the outer ring (B13) in the axial direction (A), the central shaft (B11) passes through the housing (10), the outer ring (B13) is disposed at the first end of the central shaft (B11), and the second end of the central shaft (B11) is not covered by the outer ring (B13); Along the axial direction (A), the first-stage sun gear (GS1) is partially fitted around the outer periphery of the outer ring (B13) and partially fitted around the outer periphery of the area of ​​the central shaft (B11) not covered by the outer ring (B13).

2. The hub drive system according to claim 1, characterized in that, One end of the outer ring (B13) in the axial direction (A) has a flange (B13f) that protrudes radially outward from the outer ring, the flange (B13f) being used to connect to the rim.

3. The hub drive system according to claim 1, characterized in that, In the axial direction (A), the secondary sun gear (GS2) is fitted around the outer periphery of the outer ring (B13) and close to the primary sun gear (GS1).

4. The hub drive system according to claim 1, characterized in that, The hub drive system also includes a braking device (20) that is partially connected to the first-stage sun gear (GS1) in a non-rotatable manner, thereby enabling the transmission of braking torque to the first-stage sun gear (GS1) during braking operations.

5. The hub drive system according to claim 4, characterized in that, The braking device (20) is a drum brake device, which includes a brake drum (21) and brake pads (22). The brake drum (21) is connected to the primary sun gear (GS1) in a non-rotatable manner, and the brake pads (22) are connected to the housing. In the non-braking state, the brake pad (22) does not contact the brake drum (21). In the braking state, the brake pad (22) presses against the inner peripheral wall of the brake drum (21).

6. The hub drive system according to claim 4, characterized in that, The inner cavity of the housing (10) has an annular first partition wall (W1) and a second partition wall (W2) connected to the inner peripheral wall of the housing (10) and spaced apart along the axial direction (A) of the housing (10). The first partition wall (W1) and the second partition wall (W2) divide the inner cavity of the housing (10) into three chambers along the axial direction (A). The three chambers are a brake chamber (R1), a motor chamber (R2) and a gear chamber (R3). The braking device (20) is located inside the braking chamber (R1). The motor (E) is located inside the motor compartment (R2). The primary planetary carrier (GC1), the primary ring gear (GR1), the secondary sun gear (GS2), the secondary planetary carrier (GC2), and the secondary ring gear (GR2) are located within the gear chamber (R3). The primary sun gear (GS1) extends from the gear chamber (R3) through the motor chamber (R2) to the brake chamber (R1).

7. The hub drive system according to claim 6, characterized in that, The housing (10) includes an intermediate housing (11), a first cover (12), a second cover (13), and a support plate (14). The intermediate shell (11) is cylindrical, and open openings are formed at both ends along the axial direction (A). The second partition wall (W2) is located on the inner periphery of the intermediate shell (11). The first cover (12) and the second cover (13) are respectively installed at the two ends of the intermediate housing (11). The first partition wall (W1) is located on the inner periphery of the first cover (12). The support plate (14) is mounted on the end of the first cover (12) away from the first partition wall (W1) in the axial direction (A). Along the axial direction (A), the area between the first cover (12) and the first partition wall (W1) forms the brake chamber (R1), the area between the first partition wall (W1) and the second partition wall (W2) forms the motor chamber (R2), and the area between the second partition wall (W2) and the second cover (13) forms the gear chamber (R3).

8. The hub drive system according to claim 6, characterized in that, A first bearing (B21) is provided between the first partition wall (W1) and the first-stage sun gear (GS1), and a second bearing (B22) is provided between the second partition wall (W2) and the first-stage sun gear (GS1).

9. The hub drive system according to claim 8, characterized in that, An annular first seal (S1) is provided between the second partition wall (W2) and the first-stage sun gear (GS1). The first seal (S1) is located on the side of the second bearing (B22) closer to the first partition wall (W1) in the axial direction (A). An annular second seal (S2) is provided between the hub bearing (B1) and the first-stage sun gear (GS1), and the second seal (S2) is located on the axial direction (A) at the end of the outer ring (B13) near the first partition wall (W1).

10. The hub drive system according to claim 2, characterized in that, An annular third seal (S3) is provided between the flange (B13f) and the housing (10).

11. The hub drive system according to claim 2, characterized in that, A third bearing (B23) is provided between the secondary sun gear (GS2) and the outer ring (B13).

12. The hub drive system according to claim 1, characterized in that, A thrust bearing (B24) is provided between the primary planetary carrier (GC1) and the secondary planetary carrier (GC2).

13. The hub drive system according to claim 6, characterized in that, The second partition wall (W2) is partially stepped, such that the second partition wall (W2) includes an annular stepped portion (Ws), the stepped portion (Ws) including a stepped peripheral wall (Ws1) and a stepped end wall (Ws2). The outer peripheral wall of the primary gear ring (GR1) is connected to the stepped peripheral wall (Ws1) with an interference fit, and one end of the primary gear ring (GR1) abuts against the stepped end wall (Ws2).

14. The hub drive system according to claim 13, characterized in that, An elastic retaining ring (40) is provided at the other end of the primary gear ring (GR1), which can prevent the primary gear ring (GR1) from disengaging from the stepped portion (Ws). The inner circumferential side of the stepped peripheral wall (Ws1) is provided with an annular groove, and the elastic retaining ring (40) is disposed in the annular groove.

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