Forward and reverse rotation two-gear speed change hub motor, circulating oil cooling and speed ratio optimization

Abstract

The invention discloses a double-speed motor structure for realizing two-gear speed change by utilizing positive and negative rotation of a motor rotor, and a speed ratio range required by smooth gear shifting. A planetary reducer of the motor comprises an input sun gear, a primary planet gear, a secondary planet gear, a gear ring, an output sun gear, two sets of one-way clutches and a planet carrier. Under the limit of the maximum vehicle speed of 32 km / h or 45 km / h, the two-gear speed ratio of the motor is set between 1.4 and 2.2, so that the motor is selected to actively shift gears within the vehicle speed range of 15-28 km / h. The planet carrier of the motor has a torque limiting function, so that reverse rotation can be unlocked after reverse rotation self-locking of wheels exceeds a set torque. Furthermore, the motor is provided with an oil storage bin and a drainage pipe, cooling oil under the action of centrifugal force is collected and reversely flows back to a motor shaft, and circulating lubrication and internal cooling are conducted on the gear and the motor.

Description

Technical Field

[0001] The invention belongs to the field of electric two-wheeled vehicles, and particularly relates to an improved optimization of a bicycle hub motor, in particular to an electric vehicle hub motor that utilizes forward and reverse speed changes of the motor. Background Art

[0002] In Europe and North America, electric-assisted bicycles are classified according to regulations, and the maximum speed limits are increased to 20MPH and 28MPH categories, that is, the maximum speeds are 32km / h and 45km / h. The original intention of electric-assisted bicycles is to use motors as a supplement to human power without losing the fun of riding. Under the premise of miniaturization and lightweight of the power-assisted motor (the weight of bicycle parts is measured in grams), the single-speed hub motor cannot meet the power-assisted requirement of 45km / h.

[0003] Patent No. 2007200020424, in the dual-speed electric vehicle hub motor that uses the motor to change speed in forward and reverse rotation, when the hub reverses, it will be locked by two sets of one-way clutches. When the reverse torque on the wheel is large enough, the reduction gear will be damaged; there is a delay when the motor switches forward and reverse. The larger the rotor's rotational inertia, the longer the delay will be, which seriously affects the riding experience. How to reasonably choose the speed ratio and shifting time of the two gears to minimize the delay, frustration and energy consumption braking; existing single-speed hub motors are all lubricated with grease For planetary gears, after the grease is squeezed out by the meshing gears, the impact on the nylon planetary gears is not too serious. However, for multi-speed hub motors, grease is not suitable for open steel tooth transmission. If lubricating oil is used, a large amount will increase the rotor assistance, while a small amount will all adhere to the inner wall of the motor housing under centrifugal force, resulting in insufficient lubrication of the steel teeth. The front fork of a conventional bicycle has an opening of 100mm, and the rear fork has an opening of 135mm. The rear hub motor must also leave axial space for the speed flywheel. How to mass-produce and install a speed hub motor of no less than 250 watts? Summary of the invention

[0004] The present invention is based on the existing hub motor of electric vehicles, especially improves and optimizes Patent No. 2007200020424 to achieve mass production.

[0005] First, the forward rotation of the wheel is defined as the forward rotation of the motor housing. When the wheel moves backward and reverses, the wheel cannot reverse because the two sets of one-way clutches are connected to different gear ratios and are both engaged with the gear. When the reverse torque on the wheel is sufficient, the gear will inevitably be damaged. To solve this problem, the planetary carrier must have controllable torque and cannot be fixed on the motor shaft and not rotate. Here, a torque limiting structure is introduced.

[0006] A disc spring (with small axial size and large elastic force) is provided to provide preload torque. The planet carrier can rotate on the motor shaft. A slip ring is provided between the disc spring and the planet carrier. The slip ring is spline-connected on the motor shaft and can slide but cannot rotate. Steel balls are provided between the slip ring and the planet carrier to transmit torque. Corresponding steel ball grooves are provided on the slip ring and the planet carrier.

[0007] When the torque on the planet carrier exceeds the torque of the preloaded disc spring on the slip ring, the steel ball rolls out of the groove (or the groove is separated from the steel ball), the planet carrier rotates, the ball returns to the groove, continues to slip, and the planet carrier continues to rotate. The planet carrier is preferably made of powder alloy to reduce weight.

[0008] Furthermore, the steel balls can be eliminated, and the planet carrier and the slip ring can directly contact each other to transmit torque. When the set torque is exceeded, the slip ring is pushed open by the inclined surface, and the planet carrier rotates.

[0009] As mentioned above, the planet carrier must be axially limited on the motor shaft based on assembly and processing requirements. At the same time, the number of teeth of the input sun gear may not be limited by the diameter of the motor shaft. The through motor shaft is optimized and improved into a disconnected spline half-shaft and stator half-shaft (a two-section motor shaft), that is, the stator half-shaft supports the motor, and the spline half-shaft supports the planet carrier and the torque limiting assembly and gear.

[0010] Furthermore, the motor shaft can also be composed of a stator half shaft, a spline half shaft, a rotor sun gear and a bearing, which is a three-section motor shaft, so that the rotor sun gear can increase the reduction ratio with a smaller number of teeth, such as a nine-tooth sun gear.

[0011] In order to match the seven-speed flywheel with the 135mm rear fork, the axial size of the hub motor is limited to about 85mm. Therefore, the axial size of the planetary reduction and one-way clutch is required to be as small as possible.

[0012] The primary planetary gear and the secondary planetary gear are arranged on both sides of the planetary carrier, and the planetary bearings are fixed to the planetary carrier by screws or spin rivets, without occupying effective axial space.

[0013] The inner ring (or outer ring) of the second clutch is integrated with the output sun gear, which effectively saves axial space.

[0014] An adapter ring is provided to connect the ring gear and clutch one, the rotor torques output by clutch one and clutch two are applied to the motor cover or motor housing, and the inner rings or outer rings of the two sets of clutches are fixed in the same place, and the two sets of clutches are arranged in radial overlapping manner (concentric), which saves effective axial space and reduces the radial size of clutch one, making assembly easier.

[0015] In order to reduce the frequent switching of the motor forward and reverse gears, the speed ratio and shifting timing of the two gears must be reasonably selected. In this industry, the regulations limit the maximum vehicle speed at which the motor is powered off to three speeds: 25km / h, 32km / h, and 45km / h. Therefore, for the latter two, the shifting timing is set within the vehicle speed range of 15-28km / h. According to the cadence (pedaling frequency) and cadence acceleration (or vehicle speed acceleration, this motor has a built-in speed sensor) and the gear selected by the power assist, the gear should be selected to reverse the gear, and it should not be limited to a very small speed range. For example, when riding at low cadence and low torque, and the low acceleration exceeds 15km / h, when the cadence decreases or the crank is at the upper and lower dead points (torque is zero), the rotor slides and stops and then reverses, and the motor shifts up to a high gear (low reduction ratio); when the cadence is high and the torque is high, when the acceleration reaches 28km / h, the rotor stops, energy consumption brakes, and the rotor reverses and shifts up; similarly, when the vehicle speed decreases, the gear is actively downshifted when the opportunity arises.

[0016] Therefore, the optimal speed ratio (ratio between low speed gear and high speed gear) must be set so that the motor can smoothly shift gears between 18 and 28 km / h (45 km / h speed limit mode) or 15 and 22 km / h (32 km / h speed limit mode). If both speed limit modes are to be taken into account, the speed ratio should be set between 1.4 and 2.2, preferably 1.70 ± 0.3.

[0017] Furthermore, for the 18-slot, 10-pole outer rotor hub motor commonly used in the industry, the maximum rotor speed should be controlled below 2200 rpm. For wheels larger than 15 inches (circumference larger than 1.5 meters), 45 km / h corresponds to a wheel speed of 500 rpm and 375 rpm (26-inch wheels), so the transmission ratio (reduction) of the rotor high gear is preferably 4.5±0.8, and the transmission ratio (reduction) of the low gear is preferably 8.0±0.8.

[0018] Furthermore, in order to improve the power density, the transmission ratio can be further increased, such as using an inner rotor or a 12-slot 7-pole outer rotor, and correspondingly increasing the number of teeth of the rotor sun gear (input sun gear) to 9. The ring gear can be matched with the primary planetary gear or the secondary planetary gear, and the rotor speed can be increased to about 4000rpm.

[0019] In order to increase the duration of high-power output and ensure sufficient lubrication of steel teeth, different from the natural air cooling and grease-lubricated gears of hub motors in this industry, the present invention adopts active circulating oil cooling and lubrication, that is, with the help of the centrifugal force generated by the rotation of the motor housing, the cooling and lubricating oil is collected, and sent back to the rotating axis through a drainage pipe (guide pipe or return pipe), splashing lubrication and cooling from the center to the outside.

[0020] Under the action of centrifugal force, the cooling oil will accumulate on the inner wall of the motor housing. A window is opened on the motor housing, and an oil storage tower is set outside the window to form an oil storage tank to collect the cooling oil. Furthermore, the oil storage tower and the motor housing are integrally formed (die-cast), and the oil storage tank is machined or formed on the inclined top of the mold. The bottom of the oil storage tower is set to a funnel-shaped slope or arc surface to reduce the projection area of ​​the oil storage tank in the direction of centrifugal force. The bottom is connected to a drainage pipe, and the outlet of the drainage pipe is set near the motor shaft (stator half shaft or spline half shaft). When the centrifugal force is large enough, the pressure generated by the cooling oil in the oil storage tank at the bottom of the oil storage tower is greater than the pressure of the cooling oil in the drainage pipe at the bottom. Then the cooling oil flows back to the vicinity of the motor shaft along the drainage pipe, part of it flows into the gear and clutch, and part of it flows into the flow channel of the hollow motor shaft (stator half shaft and spline half shaft), and then enters the rotor and stator from the flow channel to cool the inside of the motor.

[0021] Furthermore, the motor housing is designed to be conical (the opening is larger towards the direction of the oil storage tank), which is conducive to the collection of cooling oil on the inner wall of the motor housing. Furthermore, the oil storage towers on the outer circle of the motor housing can be connected into a piece to form a raised annular belt, and the oil storage tank forms an annular groove, and the oil storage tank with an annular groove can be machined on a lathe.

[0022] Compared with the centrifugal (throwing block) automatic speed-changing hub motor, the present invention has obvious advantages in weight and axial space under the same power; another fundamental difference is that the forward and reverse type can actively shift gears when appropriate in a wide speed range, and the gear shifting can be smooth, while the centrifugal type only passively shifts gears in a very small speed range (switching quantity), and there are jerks.

[0023] Furthermore, the pedal assist system used in this motor adopts multiple physical buttons to replace the electronic throttle (rotating the handlebars to adjust the vehicle speed, which belongs to the category of motor vehicles) based on industry restrictions and safety considerations as well as ease of operation. Each button indicates the maximum vehicle speed that can be reached in cruise control (pure electric low-speed mode). The button is also used to select the assist gear (to replace operating two buttons to cycle through gear selection).

[0024] Taking the five-speed power-assist mode as an example, five buttons are set, each button represents the power-assist gear and the maximum pure electric speed. A single press indicates the selection of the power-assist gear. Long pressing the button without releasing it indicates that pure electric riding is possible (i.e. the cadence is 0). The maximum speed of the first-speed pure electric cruise is 3km / h (pushing the car when climbing a hill, self-locking when backing up), the maximum cruising speed of the second gear is 5km / h, the third gear is 8km / h, the fourth gear is 11km / h, and the fifth gear is 15km / h, which can be completed with the low speed gear of this dual-speed motor; release the button, and the motor driver adjusts the power assistance according to the cadence and the torque parameters of the middle shaft. When the cadence exceeds 90rpm, the motor-assisted speed reaches a maximum of 45km / h. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described below in conjunction with specific illustrations. The drawings in the description are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Cross-section diagram of the dual-speed hub motor and schematic diagram of the oil circulation circuit Figure 2 Schematic diagram of reduction transmission structure Figure 3 Exploded diagram of reduction transmission structure Figure 4 Schematic diagram of two-stage motor shaft and modular assembly Figure 5 Schematic diagram of the positions of two sets of one-way clutches Figure 6 Explosion diagram of the planet carrier torque limiting structure Figure 7 Cross-section of three-section motor shaft and dual-speed motor Figure 8 Schematic diagram of three-stage motor shaft reduction transmission structure Fig. 9 The cross-section of the dual-speed motor and the schematic diagram of the oil circulation circuit after the motor housing is optimized Fig.10 Schematic diagram of the appearance of a dual-speed hub motor Fig.11 A cross-sectional view of a motor housing assembly with an annular groove as the oil storage tank 1 stator half shaft, 2 spline half shaft, 3 rotor, 4 planet carrier, 5 steel ball, 6 slip ring, 7 disc spring, 8 input sun gear, 9 primary planet gear, 10 secondary planet gear, 11 ring gear, 12 output sun gear, 13 clutch one, 14 clutch two, 15 planet gear bearing, 16 adapter ring, 17 screw, 18 drainage pipe, 19 oil storage tank, 20 motor housing, 21 motor cover, 22 oil storage tower, 23 nine-tooth sun gear, 24 counterweight rib. DETAILED DESCRIPTION

[0027] The following will fully describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0029] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0030] like Figure 1 , Figure 2 , Figure 3 As shown, the motor shaft is composed of two sections, the stator half shaft (1) is inserted into the spline half shaft (2) to form the motor shaft, the stator half shaft (1) is hollow, one end is a channel for leading out the motor wire, and the other end and the blind hole (or through hole) of the spline half shaft (2) form a flow channel for cooling oil. Furthermore, the contact surface of the end of the stator half shaft (1) and the spline half shaft (2) can be provided with a meshing keyway to prevent mutual rotation, thereby reducing tooling and processes in motor testing.

[0031] A window is provided on the wall of the motor housing (20), and the oil storage tower (22) forms an oil storage bin (19). The bottom of the oil storage tower (22) is an inclined surface or an arc surface, and the bottom is connected to a drainage pipe (18). The drainage pipe (18) is inserted from the motor cover (21) to the spline half shaft (2). When the motor housing (20) rotates at a sufficient speed, the centrifugal force presses the cooling oil into the drainage pipe (18), and part of the cooling oil flows into the gear and the clutch, and part of the cooling oil flows into the flow channel of the motor shaft, and then enters the rotor (3) and the stator from the flow channel. The cooling oil is collected on the inner wall of the motor housing and flows back to the oil storage bin (19). Furthermore, a dynamic balancing counterweight is added to the symmetrical surface of the oil storage tower on the motor housing.

[0032] The primary planetary gear (9) and the secondary planetary gear (10) are fixed together by screws (17) to form a double-linked tooth. The planetary carrier (4) is arranged in the middle of the double-linked tooth. The planetary bearing (15) is fixed in the planetary carrier (4) by screws (17).

[0033] The output sun gear (12) and the inner ring (ratchet seat) of the second clutch (14) are integrated into one body; one end of the adapter ring (16) is interference-connected with the ring gear (11), and the other end is interference-connected with the outer ring of the first clutch (13), so as to transmit the torque of the ring gear (11) to the outer ring of the first clutch.

[0034] The number of teeth of the input sun gear (8) is referred to as Z1, the number of teeth of the primary planet gear (9) is referred to as Z2, the number of teeth of the secondary planet gear (10) is referred to as Z3, the number of teeth of the ring gear (11) is referred to as Z4, and the number of teeth of the output sun gear (12) is referred to as Z5.

[0035] The two-way transmission chains are as follows: Z1 reverses, Z2 and Z3 rotate forward, Z4 rotates forward, clutch one is connected, the motor housing rotates forward (wheels move forward), Z5 reverses, the inner ring of clutch two idles, the reduction ratio = (Z2 / Z1) * (Z4 / Z3), which is the low speed gear; Z1 rotates forward, Z2 and Z3 reverse, Z4 reverses, the inner ring of clutch one idles, Z5 rotates forward, clutch two is connected, the motor housing rotates forward, the reduction ratio = (Z2 / Z1) * (Z5 / Z3), which is the high speed gear; the speed ratio between low speed and high speed gear is Z4 / Z5.

[0036] like Figure 4 As shown, the upper figure shows that the spline half shaft (2) is assembled with the reduction gear and the inner and outer rings of the clutch into a whole, which is modular; the lower figure shows that the stator half shaft (1) is assembled with the motor stator and rotor into a whole, which is modular.

[0037] like Figure 5 As shown, a schematic diagram of the arrangement of two sets of clutches is shown, in which the two sets of clutches are arranged in radial overlap (concentric circles). In this example, clutch one (13) is a roller one-way clutch, and clutch two (14) is a ratchet one-way clutch. The serration ring of clutch two (14) is threadedly connected to the motor cover (21), and the inner ring of clutch one (13) is interference-connected to the motor cover (21).

[0038] like Figure 6 As shown, the torque limiting structure of the planet carrier (4) includes a steel ball (5), a slip ring (6), a disc spring (7), and a retaining ring. The planet carrier (4) is sleeved on the end of the spline half shaft (2) and can be rotated axially to limit the axial limit. The slip ring (6) slides on the spline half shaft (2) and cannot rotate. The planet carrier (4) and the slip ring (6) both have bead grooves that match the steel ball (5). The bead groove on the slip ring (6) is shallow. The steel ball (5) transmits the torque on the planet carrier (4). The slip ring (6) compresses the disc spring (7). The slip ring (6) moves axially to disengage from the steel ball (5). The planet carrier (4) and the steel ball (5) rotate to the next bead groove to reset. The disc spring (7) is a standard part ¢14*¢28*1.25.

[0039] The slip ring and the spline half shaft are shown in the figure as a polygonal fit. It is also possible to rub out the external spline on the spline half shaft and pull the internal spline of the slip ring.

[0040] like Figure 7 , Figure 8 As shown, the three-section motor shaft comprises a stator half shaft, a spline half shaft, a nine-tooth sun gear (23) and a bearing, the nine-tooth sun gear (23) is connected to a rotor (an outer rotor or an inner rotor) as an input sun gear, the ring gear meshes with the primary planetary gear as a high-speed gear, and the output sun gear meshes with the secondary planetary gear as a low-speed gear.

[0041] The planetary bearings are fixed in the planetary carrier by spin rivets, saving axial space.

[0042] The figure shows that Z1=9, Z2=33, Z3=9, Z4=78, Z5=33; the reduction ratio of high gear: (Z2 / Z1)*(Z4 / Z2)=8.67; the reduction ratio of low gear: (Z2 / Z1)*(Z5 / Z3)=13.45.

[0043] For example, for a 26-inch wheel with a circumference of 2 meters, the wheel speed is 375rpm at 45km / h, then the speed of the rotor in high gear is 375*8.67=3251rpm, which is suitable for an inner rotor or an outer rotor with 12 slots and 7 pairs of poles.

[0044] like Fig. 9 As shown, the circulation path of the cooling oil, the stator half shaft is changed to the right flywheel end to lead out the motor line, the motor shell is optimized and has a conical shape, which is more conducive to the collection of cooling oil. The bottom of the oil storage tower (22) is an arc surface, and the drainage pipe (18) is inserted into the motor shell (both the inlet and outlet ends are on the motor shell) to form an integral component, which is convenient for subsequent assembly.

[0045] Book Figure 1 The motor cover shown is threadedly connected to the flywheel, which is suitable for 7-speed and below flywheels. As shown in this figure, a serrated ring is installed at the end of the motor cover and a cassette flywheel is configured. The smallest flywheel 11T is suitable for chainrings above 44T, which is conducive to a pedaling frequency of 90rpm to reach a speed of 45km / h.

[0046] like Fig.10 As shown, the schematic diagram of the appearance of the dual-speed motor, the motor housing is optimized to be conical, which is conducive to the collection of cooling oil, the outer diameters of the spoke flanges of the motor housing are different, the drainage pipe (18) is placed outside the motor housing, saving the volume of the motor housing, the oil storage tower (22) is integrally formed with the motor housing, and the symmetrical surface of the oil storage tower (22) has a counterweight rib (24) for maintaining dynamic balance to enhance heat dissipation.

[0047] like Fig.11 As shown, a cross-sectional view of a motor housing and a drainage pipe after assembly, the oil storage towers on the outer periphery of the motor housing are connected into one piece, forming a raised annular belt, and the oil storage tank forms an annular belt groove. The drainage pipes are arranged symmetrically to ensure the dynamic balance of the assembly.

[0048] In summary, when the dual-speed motor is installed on the frame, the forward and reverse rotation of the rotor will cause the fixed torque of the motor shaft to commutate. Since there is an installation gap between the frame tail hook and the motor shaft, a positioning gasket needs to be installed and the motor shaft should be locked on the tail hook.

[0049] The above descriptions are only several specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be included in the protection scope of the present invention.

Claims

1. A hub motor that realizes two-speed shifting (dual speed) by forward and reverse rotation of the motor rotor, comprising a motor, two fixed-axis planetary gears, two sets of sun gears, a gear ring, two sets of one-way clutches, a disconnecting motor shaft, a bearing, a planetary carrier, a disc spring, a slip ring, a motor housing, a motor cover, etc.; further, the hub motor uses oil to actively cool the motor and lubricate the gears, and its characteristics include: The two-way fixed-axis planetary gear has two transmission chains with different transmission ratios and directions. When the motor rotor rotates forward or reverse, the two transmission chains are connected by two sets of one-way clutches respectively. The two sets of one-way clutches output two speeds respectively to drive the motor housing to rotate forward (the wheels move forward), and actively shift gears within the set vehicle speed range; when the motor hub (wheel) reverses, it will be locked by the two sets of one-way clutches, gears and planetary carriers (with torque limitation). Only when the reverse torque applied to the hub exceeds the set threshold, that is, the torque on the planetary carrier exceeds the set value, the planetary carrier will rotate around the motor shaft, and the motor hub (wheel) can reverse.

2. The dual-speed hub motor according to claim 1, characterized in that: The active shifting interval is set between vehicle speeds of 15 and 28 km / h; the speed ratio of the two gears, that is, the ratio of the transmission ratio of the low gear to the high gear, is set between 1.4 and 2.2, preferably 1.70±0.3; further, for an 18-slot 10-pole outer rotor motor, the transmission ratio (deceleration) of the rotor high gear is preferably 4.5±0.8, and the transmission ratio (deceleration) of the low gear is preferably 8.0±0.

8.

3. The dual-speed hub motor according to claim 1, characterized in that: The motor shaft is a non-through shaft, and the motor shaft includes two sections (two-section type), namely, a stator half shaft and a spline half shaft. The stator half shaft supports the motor, and the spline half shaft supports the planetary carrier, the torque limiting assembly and the gear. Furthermore, the motor shaft can also be composed of three sections (three-section type), namely, a stator half shaft, a spline half shaft and a rotor sun gear, so that the rotor sun gear increases the transmission ratio with a smaller number of teeth.

4. The dual-speed hub motor according to claim 1, characterized in that: The planetary carrier with torque limiting function also includes steel balls, slip rings, disc springs, and other components. The slip rings can slide axially on the spline half shaft and are restricted from rotating radially. The pre-pressure for torque limitation is provided by the disc springs, and the steel balls transmit the pre-pressure. Furthermore, the steel balls can be eliminated and the pre-pressure can be transmitted by the contact between the planetary carrier and the slip ring inclined surface or arc surface.

5. The dual-speed hub motor according to claim 1 is characterized in that: the output sun gear and the inner ring (or outer ring) of the second clutch are arranged as an integrated unit to save space; the planetary gear bearings are fixed in the planetary carrier by screws or spin rivets to save axial space; the planetary carrier is preferably made of powder alloy to reduce weight and processing cost; the secondary planetary gear is fixed to the primary planetary gear by screws to form a double-linked tooth.

6. The dual-speed hub motor according to claim 1, characterized in that: An adapter ring is provided between the ring gear and clutch one to transmit the torque of the ring gear to clutch one; the torque transmitted by clutch one and clutch two is applied to the motor housing or motor cover for easy assembly; clutch one and clutch two are arranged in radial overlap (concentric) to save axial space.

7. The dual-speed hub motor according to claim 1 is further characterized in that: an appropriate amount of cooling oil is injected into the motor, and the cooling oil will accumulate on the inner wall of the motor housing under the action of centrifugal force. The motor housing and components can collect the cooling oil accumulated on the inner wall and reversely flow it back to the vicinity of the motor shaft, so that the cooling oil circulates and lubricates the transmission components from the axis centrifugally; the cooling oil can also flow into the inside of the motor shaft, and then be injected into the stator and rotor from the internal flow channel to circulate and cool the inside of the stator and rotor.

8. The dual-speed hub motor according to claim 7, characterized in that: An oil storage bin with a depression (depression on the inner wall and protrusion on the outer wall) is provided on the motor housing to collect cooling oil. The oil storage bin is connected to a drainage pipe, and an outlet of the drainage pipe is arranged near the motor shaft.

9. The dual-speed hub motor according to claim 8, characterized in that: A window is opened on the motor housing to form an oil storage tank with the oil storage tower to collect the refluxed cooling oil; The bottom of the oil storage bin is preferably an inclined surface (or a funnel-shaped cone or arc surface) to reduce the projection area of ​​the oil storage bin in the direction of centrifugal force. The pressure generated by the centrifugal force sends the cooling oil back to the rotation axis along the drainage pipe.

10. The dual-speed hub motor according to claim 8 is further characterized in that: the oil storage tower and the motor shell are integrally formed, the motor shell is conical (further, the outer diameters of the spoke flanges of the motor shell are not the same), the drainage pipe is placed outside the motor shell, and counterweight ribs for maintaining dynamic balance are provided on the symmetric plane of the oil storage tower; further, multiple oil storage towers are evenly distributed on the circumference or the oil storage towers are connected to form a ring belt on the circumference (that is, the oil storage bins form a ring belt groove), and multiple symmetrically arranged drainage pipes can be connected to ensure the dynamic balance of the assembly.

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