A mid-mounted motor and electric power-assisted bicycle

Abstract

The present invention discloses a mid-mounted motor and an electric power-assisted bicycle, and relates to the field of electric bicycles. The mid-mounted motor includes a housing, a stator, a rotor assembly, a sun gear, a planetary gear assembly, a transmission assembly, a clutch assembly, and a central shaft, wherein the stator is fixedly connected to the housing; the rotor is coaxially and rotatably arranged inside the stator; the sun gear is fixedly penetrated through the rotor assembly and is rotatably connected to the housing; the planetary gear assembly includes an inner gear ring, a double-linked planetary gear meshed with the inner gear ring, and a planetary carrier connected to the double-linked planetary gear, the inner gear ring is fixedly connected to the housing, the double-linked planetary gear meshes with the sun gear, the planetary carrier is rotatably connected to the sun gear and fixed to the double-linked planetary gear; the transmission assembly includes a pulley and a synchronous belt connected to the pulley, the pulley is connected to the planetary carrier; the clutch assembly is connected to the synchronous belt; the central shaft extends along the axial direction of the sun gear and is connected to the clutch assembly. By adopting the planetary gear assembly, the motor torque can be increased while reducing the motor speed.

Description

Technical Field

[0001] The present invention relates to the field of electric bicycles, and in particular to a mid-mounted motor and an electric power-assisted bicycle. Background Art

[0002] As an auxiliary means of transportation, power-assisted bicycles are equipped with motors and power-assisted systems, which can realize the integration of human riding and motor assistance. At present, power-assisted bicycles have increasingly become an important means of transportation for people to travel, and the motor of power-assisted bicycles is particularly important as the main power source in the power-assisted device. In the prior art, the primary reduction gears of traditional motors used in power-assisted bicycles mostly use parallel teeth and nylon teeth, resulting in low working efficiency, narrow motor high-efficiency platform, large tooth slot torque, small torque, high temperature rise, poor reliability and low strength of nylon teeth. Summary of the invention

[0003] The object of the present invention is to provide a mid-mounted motor, which is light in weight, small in size and can increase the torque of the motor while reducing the motor speed.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] A mid-mounted motor, comprising:

[0006] chassis;

[0007] A stator, the stator being fixedly connected to the casing;

[0008] A rotor assembly, the rotor assembly is coaxially and rotatably disposed inside the stator;

[0009] A sun gear, the sun gear is fixedly disposed through the rotor assembly and is rotatably connected to the casing;

[0010] A planetary gear assembly, comprising an inner gear ring, duplex planetary gears meshing with the inner gear ring, and a planet carrier connected to the duplex planetary gears, wherein the inner gear ring is fixedly connected to the housing, the duplex planetary gears meshing with the sun gears, and the planet carrier is rotatably connected to the sun gears and fixedly connected to the duplex planetary gears;

[0011] A transmission assembly, the transmission assembly comprising a pulley and a synchronous belt drivingly connected to the pulley, the pulley being drivingly connected to the planet carrier;

[0012] A clutch assembly, the clutch assembly being connected to the synchronous belt transmission;

[0013] A middle shaft extends along the axial direction of the sun gear and is connected to the clutch assembly.

[0014] Optionally, the planetary gear assembly further includes a connecting pin and a support frame, wherein the connecting pin is rotatably inserted into the double-linked planetary gear and has two ends respectively fixed to the planetary frame and the support frame, and the support frame is connected to the pulley.

[0015] Optionally, the central motor further includes a first housing, the housing and the inner gear ring are respectively fixed on two sides of the first housing, and the planet carrier and the central shaft are both rotatably connected to the first housing.

[0016] Optionally, the clutch assembly includes an output pulley and a second inner wheel coaxially arranged inside the output pulley, a plurality of second rollers are evenly spaced along the circumferential direction of the second inner wheel between the second inner wheel and the inner wall of the output pulley, and the second rollers can roll between the second inner wheel and the output pulley; the second inner wheel is keyed to the center shaft, and the output pulley is connected to the synchronous belt drive and is rotatably connected to the center shaft.

[0017] Optionally, a plurality of third rollers are evenly spaced apart along the circumferential direction of the second inner wheel between the inner wall of the second inner wheel and the output pulley, the third rollers are capable of rolling between the second inner wheel and the output pulley, the third rollers are alternately arranged with the second rollers and the diameter of the third rollers is smaller than the diameter of the second rollers.

[0018] Optionally, the clutch assembly further comprises a retaining frame, which is coaxially disposed between the second inner wheel and the output pulley and is capable of abutting against the plurality of second rollers and the plurality of third rollers along the axial direction of the second inner wheel.

[0019] Optionally, the rotor assembly includes a rotor core and a plurality of magnets embedded in the rotor core, the plurality of magnets being evenly spaced along the circumference of the rotor core; a plurality of buckling points are arranged on one end surface of the rotor core along the axial direction, the plurality of buckling points are evenly spaced along the circumference of the rotor core, one buckling point is arranged between each adjacent two magnets, and a plurality of grooves are arranged on the other end surface of the rotor core along the axial direction, the plurality of grooves corresponding one-to-one to the positions of the plurality of buckling points.

[0020] Optionally, the rotor core is provided with a plurality of circular through holes evenly spaced apart along the axial direction, and the plurality of circular through holes all extend along the axial direction of the rotor core.

[0021] Optionally, the central motor further includes a detection element, wherein the detection element is fixedly connected to the central shaft, and the detection element is used to detect the torque of the central shaft.

[0022] Another object of the present invention is to provide an electric power-assisted bicycle, the motor of which is light in weight and small in size and can increase the torque of the motor while reducing the motor speed.

[0023] To achieve this object, the present invention adopts the following technical solutions:

[0024] An electric power-assisted bicycle comprises the above-mentioned mid-mounted motor.

[0025] The beneficial effects of the present invention are as follows: the mid-mounted motor provided by the present invention is used for an electric power-assisted bicycle. When powered on, the rotor can rotate relative to the stator, and then the rotor can drive the sun gear to rotate. The sun gear drives the double-linked planetary gear to rotate in the inner gear ring. At the same time, the double-linked planetary gear can drive the planet carrier to rotate, and finally the synchronous belt is driven by the pulley. The synchronous belt and the clutch assembly are connected in transmission to transmit power. By adopting the cooperation of the double-linked planetary gear and the inner gear ring, the structure of the planetary gear assembly is compact. At the same time, the inner gear ring has a large carrying capacity and can accommodate the double-linked planetary gear inside, so that the mid-mounted motor can be light in weight and small in size. At the same time, compared with the reduction gear in the traditional motor, the use of the planetary gear assembly for power transmission can improve the transmission efficiency of the motor, and can increase the torque of the motor while reducing the motor speed. In addition, the transmission assembly is driven by the pulley and the synchronous belt. There is no relative sliding between the synchronous belt and the pulley, which can ensure an accurate transmission ratio, and the transmission noise is small, the wear resistance is good, and no oil lubrication is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional view of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0027] Figure 2 is an exploded view of a portion of the structure of the mid-mounted motor provided in the first embodiment of the present invention;

[0028] Figure 3 is a cross-sectional view of a planetary gear assembly of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0029] Figure 4 1 is a schematic diagram of the installation of the inner gear ring of the planetary gear assembly of the mid-mounted motor provided in the first embodiment of the present invention;

[0030] Figure 5 is a cross-sectional view of a transmission assembly of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0031] Figure 6 is an exploded view of a transmission assembly of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0032] Figure 7 is a cross-sectional view of a clutch assembly of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0033] Figure 8 is an exploded view of a clutch assembly of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0034] Fig. 9 is a schematic structural diagram of a rotor assembly of a mid-mounted motor provided in Embodiment 1 of the present invention;

[0035] Fig.10 is a cross-sectional view of a transmission assembly of a mid-mounted motor provided in Embodiment 2 of the present invention;

[0036] Fig.11 It is an exploded view of the transmission assembly of the mid-mounted motor provided in the second embodiment of the present invention.

[0037] In the figure:

[0038] 1- housing; 2- stator;

[0039] 3- rotor; 31- rotor core; 311- buckle point; 312- circular through hole; 313- through hole; 32- magnetic steel;

[0040] 4-Sun gear;

[0041] 5-planetary gear assembly; 51-inner ring gear; 52-double planetary gear; 53-planet carrier; 54-connecting pin; 55-support frame;

[0042] 6-transmission assembly; 61-pulley; 62-synchronous belt; 63-tensioner; 64-first inner wheel; 641-first arc groove; 642-semi-arc groove; 65-first roller; 66-first bearing; 67-baffle;

[0043] 7-clutch assembly; 71-output pulley; 72-second inner wheel; 73-second roller; 74-third roller; 75-cage;

[0044] 8-middle shaft; 9-first housing; 10-sprocket; 11-second housing; 12-bearing seat; 13-controller; 14-circuit board; 15-bracket; 16-oil seal. DETAILED DESCRIPTION

[0045] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0049] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0050] Embodiment 1

[0051] like Figure 1-Figure 6As shown, the central motor includes a casing 1, a stator 2, a rotor assembly 3, a sun gear 4, a planetary gear assembly 5, a transmission assembly 6, a clutch assembly 7 and a central shaft 8, wherein the stator 2 is fixedly connected to the casing 1; the rotor assembly 3 is coaxially and rotatably arranged inside the stator 2; the sun gear 4 is fixedly penetrated by the rotor assembly 3 and is rotatably connected to the casing 1; the planetary gear assembly 5 includes an inner ring gear 51, a double planetary gear 52 meshing with the inner ring gear 51 and a planet carrier 53 connected to the double planetary gear 52, the inner ring gear 51 is fixedly connected to the casing 1, the double planetary gear 52 is meshed with the sun gear 4, the planet carrier 53 is rotatably connected to the sun gear 4 and fixed to the double planetary gear 5; the transmission assembly 6 includes a pulley 61 and a synchronous belt 62 transmission-connected to the pulley 61, the pulley 61 is transmission-connected to the planet carrier 53; the clutch assembly 7 is transmission-connected to the synchronous belt 62; the central shaft 8 extends along the axial direction of the sun gear 4 and is connected to the clutch assembly 7. It can be understood that when the power is turned on, the rotor assembly 3 can rotate relative to the stator 2, and then the rotor assembly 3 can drive the sun gear 4 to rotate, and the sun gear 4 drives the double planetary gear 52 to rotate in the inner gear ring 51, and the double planetary gear 52 can drive the planet carrier 53 to rotate, and finally drive the synchronous belt 62 through the pulley 61, and the synchronous belt 62 and the clutch assembly 7 are connected to transmit power. By using the cooperation of the double planetary gear 52 and the inner gear ring 51, the structure of the planetary gear assembly 5 is compact, and the inner gear ring 51 has a large carrying capacity and can accommodate the double planetary gear 52 inside, so that the weight of the central motor is light and the volume is small. At the same time, compared with the reduction gear in the traditional motor, the use of the planetary gear assembly 5 for power transmission can improve the transmission efficiency of the motor, and can reduce the motor speed while increasing the torque of the motor; in addition, the transmission assembly 6 is driven by the pulley 61 and the synchronous belt 62, and there is no relative sliding between the synchronous belt 62 and the pulley 61, which can ensure an accurate transmission ratio, and the transmission noise is small, the wear resistance is good, and no oil lubrication is required.

[0052] Specifically, Figure 1-Figure 3 As shown, in order to reduce the rotational friction, one end of the sun gear 4 is rotatably connected to the housing 1 through a bearing, and a gasket is provided between the bearing and the housing 1, and the axial clearance between the sun gear 4 and the housing 1 can be adjusted through the gasket, and the planet carrier 53 is rotatably matched with the sun gear 4 through a deep groove ball bearing. In other embodiments, other structures besides bearings can also be used.

[0053] In this embodiment, the mid-mounted motor is applied to an electric power-assisted bicycle, such as Figure 2 As shown, the electric power-assisted bicycle further includes a toothed disc 10, which is connected to the middle shaft 8, and the toothed disc 10 is connected to the wheel of the electric power-assisted bicycle through a chain; at the same time, cranks are installed at both ends of the middle shaft 8, and pedals are installed on the cranks, that is, the electric power-assisted bicycle can also rotate the middle shaft 8 through the pedals to drive the wheels to rotate. In other embodiments, the mid-mounted motor can also be applied to other electric bicycles.

[0054] Specifically, Figure 2 As shown, the transmission assembly 6 also includes a tensioner 63. The tensioner 63 can adjust the tightness of the synchronous belt 62 to ensure that the synchronous belt 62 has an appropriate tension, thereby preventing the synchronous belt 62 from slipping, or preventing the synchronous belt 62 from jumping teeth or stripping teeth and coming off the pulley 61, thereby ensuring the transmission effect, and easy installation and reliable use. As for the specific structure of the tensioner 63, it is already a prior art and will not be described in detail here. In other embodiments, the tensioner 63 may not be provided, and it is sufficient to ensure that the tension of the synchronous belt 62 is appropriate.

[0055] Alternatively, if Figure 1 and Figure 3 As shown, the planetary gear assembly 5 further includes a connecting pin 54 and a support frame 55. The connecting pin 54 is rotatably inserted into the double-linked planetary gear 52 and its two ends are respectively fixedly connected to the planetary frame 53 and the support frame 55. The support frame 55 is connected to the pulley 61. It can be understood that when the sun gear 4 is meshed with the double-linked planetary gear 52 for transmission, the double-linked planetary gear 52 can drive the planetary frame 53 to rotate synchronously while rotating in the inner gear ring 51. The planetary frame 53 drives the support frame 55 to rotate through the connecting pin 54, and then the support frame 55 can transmit power to the pulley 61. In this embodiment, the sun gear 4 is inserted into the planetary frame 53, and the connecting pin 54 extends along the length direction of the sun gear 4, and is rotatably connected to the double planetary gear 52 through two deep groove ball bearings, the two deep groove ball bearings are arranged at intervals and a gasket is arranged in the middle, and the two deep groove ball bearings can be limited by the gasket, and the two sides of the two deep groove ball bearings are respectively abutted against the planetary frame 53 and the support frame 55; in addition, in order to ensure the reliable connection between the planetary frame 53 and the support frame 55, in addition to the connecting pin 54, the planetary frame 53 and the support frame 55 are also fixed by screws. In other embodiments, the planetary frame 53 and the support frame 55 can also be fixed by other means.

[0056] In this embodiment, the inner gear ring 51 and the duplex planetary gears 52 are both made of steel, which has better heat dissipation capacity and strength than ordinary nylon materials, and can extend the service life of the inner gear ring 51 and the duplex planetary gears 52. In other embodiments, the inner gear ring 51 and the duplex planetary gears 52 can also be made of other materials with better heat dissipation and greater strength.

[0057] In this embodiment, Figure 5 and Figure 6As shown, the transmission assembly 6 also includes a first inner wheel 64 coaxially arranged inside the pulley 61, and a plurality of first rollers 65 are evenly spaced between the first inner wheel 64 and the inner wall of the pulley 61 along the circumferential direction of the first inner wheel 64, and the first rollers 65 can roll between the first inner wheel 64 and the pulley 61; the first inner wheel 64 is fixedly connected to the planet carrier 53. Specifically, the first inner wheel 64 is connected to the support frame 55 through an A-type flat key. A plurality of first arc grooves 641 are spaced apart on the outer circumference of the first inner wheel 64, and the first rollers 65 can roll in the first arc grooves 641. When the sun gear 4 rotates and drives the double planetary gear 52 to rotate, the first inner wheel 64 can be driven to rotate synchronously through the rotation of the planet carrier 53 and the support frame 55. At this time, the transmission assembly 6 is in a combined state, and the first roller 65 can be pressed between the first inner wheel 64 and the pulley 61, thereby transmitting power to the pulley 61; conversely, when the pulley 61 rotates, the transmission assembly 6 is in a disengaged state, that is, the first roller 65 can roll in the first arc groove 641 on the outer periphery of the first inner wheel 64, and power cannot be transmitted between the first inner wheel 64 and the pulley 61. It can be understood that the power transmission between the first inner wheel 64 and the pulley 61 is carried out through the first roller 65, with high transmission efficiency, stable operation and low noise.

[0058] Specifically, Figure 5 and Figure 6 As shown, the transmission assembly 6 further includes a first bearing 66, which is coaxially disposed between the first inner wheel 64 and the pulley 61 and can abut against a plurality of first rollers 65 along the axial direction of the first inner wheel 64. It can be understood that the two ends of the first roller 65 abut against the limiting step of the pulley 61 and the first bearing 66, respectively, and the first roller 65 can be limited in the axial direction of the first inner wheel 64 by the first bearing 66 to prevent the first roller 65 from coming out in the axial direction of the first inner wheel 64. In other embodiments, other structures can also be used instead of the first bearing 66.

[0059] Alternatively, if Figure 1 and Figure 3 As shown, the central motor further includes a first housing 9, the housing 1 and the inner gear ring 51 are fixed on both sides of the first housing 9, and the planet carrier 53 and the middle shaft 8 are both rotatably connected to the first housing 9. Specifically, the sun gear 4 is passed through the first housing 9, one end of the middle shaft 8 is also passed through the first housing 9 and rotatably cooperates with the first housing 9 through a bearing, and the planet carrier 53 is also rotatably cooperated with the first housing 9 through a bearing. Specifically, as Figure 4As shown, the inner gear ring 51 is fixed to the first housing 9 by six stepped screws. In this embodiment, the central motor also includes a circuit board 14, which is fixed to the first housing 9 and connected to the stator 2. It also includes a second housing 11, the other end of the central axis 8 is passed through the second housing 11, the first housing 9 and the second housing 11 are fixedly connected by screws, the planetary gear assembly 5, the transmission assembly 6 and the clutch assembly 7 are all located between the first housing 9 and the second housing 11, and the planetary gear assembly 5, the transmission assembly 6 and the clutch assembly 7 can be closed and protected by the first housing 9 and the second housing 11 to avoid damage; at the same time, the end of the sun gear 4 away from the housing 1 is rotatably connected to the second housing 11 through a bearing, and the clutch assembly 7 is rotatably matched with the second housing 11 through a bearing. In other embodiments, the inner gear ring 51 can also be fixedly connected to the first housing 9 by a pin and a retaining spring.

[0060] Optionally, the central motor further comprises a detection element, which is fixedly connected to the central shaft 8 and is used to detect the torque of the central shaft 8. Figure 1 As shown, the central motor also includes a controller 13, which is fixed to the first box body 9 by screws, and the detection element is a torque sensor, which is electrically connected to the controller 13. The torque of the central shaft 8 is detected by the torque sensor and fed back to the controller 13. The controller 13 can automatically control the central motor, and the control is simple and convenient. As for the specific structure of the controller 13, it is already a prior art and will not be described here. In other embodiments, the detection element can also be other structures.

[0061] Alternatively, if Figure 1 , Figure 7 and Figure 8As shown, the clutch assembly 7 includes an output pulley 71 and a second inner wheel 72 coaxially arranged inside the output pulley 71. A plurality of second rollers 73 are evenly spaced between the second inner wheel 72 and the inner wall of the output pulley 71 along the circumferential direction of the second inner wheel 72. The second rollers 73 can roll between the second inner wheel 72 and the output pulley 71. The second inner wheel 72 is key-connected to the middle shaft 8. The output pulley 71 is transmission-connected to the synchronous belt 62 and rotationally connected to the middle shaft 8. Specifically, the output pulley 71 is rotationally connected to the second housing 11 through a bearing, and the output end of the output pulley 71 is penetrated through the second housing 11 and connected to the toothed disc 10. The output pulley 71 is rotationally connected to the middle shaft 8 through a needle bearing. At the same time, an oil seal 16 is also arranged outside the needle bearing. The oil seal 16 is sleeved on the middle shaft 8 to protect the needle bearing. It can be understood that when the output pulley 71 rotates, it can drive the toothed disc 10 to rotate, and then drive the wheel to rotate, so as to achieve the purpose of electric riding. In this embodiment, the second inner wheel 72 is provided with an inner spline, and the center shaft 8 is provided with an outer spline. The second inner wheel 72 is connected to the center shaft 8 through the spline, which can ensure a reliable connection. In other embodiments, the second inner wheel 72 and the center shaft 8 can also be connected in other ways.

[0062] Specifically, Figure 7 and Figure 8 As shown, a plurality of third rollers 74 are evenly spaced between the inner wall of the second inner wheel 72 and the output pulley 71 along the circumferential direction of the second inner wheel 72, and the third rollers 74 can roll between the second inner wheel 72 and the output pulley 71. The third rollers 74 and the second rollers 73 are alternately arranged, and the diameter of the third rollers 74 is smaller than the diameter of the second rollers 73. In this embodiment, a plurality of second arc grooves are evenly spaced on the outer periphery of the second inner wheel 72, and the third rollers 74 and the second rollers 73 can roll in the second arc grooves. When the transmission assembly 6 is able to transmit power, that is, when the pulley 61 of the transmission assembly 6 rotates, the synchronous belt 62 can drive the output pulley 71 to rotate synchronously. At this time, the clutch assembly 7 is in a disengaged state, that is, the third roller 74 and the second roller 73 can roll in the second arc groove, and the power cannot be transmitted to the second inner core wheel 72; when the pedal is stepped on and the middle shaft 8 is rotated by the crank, the middle shaft 8 drives the second inner core wheel 72 to rotate. At this time, the clutch assembly 7 is in a coupled state, that is, the third roller 74 and the second roller 73 can be pressed between the second inner core wheel 72 and the output pulley 71 to transmit power, thereby driving the output pulley 71 to rotate, and then transmitting the power to the wheel through the sprocket 10 to drive the wheel to rotate.

[0063] Specifically, the clutch assembly 7 further includes a retainer 75, which is coaxially disposed between the second inner wheel 72 and the output pulley 71 and can abut against the plurality of second rollers 73 and the plurality of third rollers 74 along the axial direction of the second inner wheel 72. It can be understood that the two ends of the second roller 73 and the plurality of third rollers 74 abut against the output pulley 71 and the retainer 75 respectively, and the second roller 73 and the third roller 74 can be limited in the axial direction of the second inner wheel 72 by the retainer 75, so as to prevent the second roller 73 and the third roller 74 from being disengaged from between the second inner wheel 72 and the output pulley 71 in the axial direction of the second inner wheel 72, thereby affecting the use effect of the clutch assembly 7. In addition, the clutch assembly 7 adopts the cooperation mode of the second roller 73 and the third roller 74, which can ensure high transmission efficiency, stable operation and low noise between the second inner wheel 72 and the output pulley 71. In other embodiments, the alternating arrangement of the second roller 73 and the third roller 74 may not be used, and only one of the second roller 73 and the third roller 74 may be used.

[0064] In this embodiment, Figure 1 As shown, the central motor further includes a bracket 15, which is sleeved on the central axis 8 and can abut against the first box body 9. The bracket 15 can limit the central axis 8 axially to prevent the central axis 8 from axially moving and affecting the use effect of the central motor; the central motor further includes a bearing seat 12, which is sleeved on the central axis 8 and fixed to the first box body 9, and is rotatably connected to the output pulley 71 through a bearing. In this embodiment, in order to reduce the weight of the central motor, the bracket 15 is made of plastic. In other embodiments, the bracket 15 can also be made of other materials.

[0065] Alternatively, if Fig. 9 As shown, the rotor assembly 3 includes a rotor core 31 and a plurality of magnetic steels 32 embedded in the rotor core 31, and the plurality of magnetic steels 32 are evenly spaced along the circumference of the rotor core 31; a plurality of buckle points 311 are arranged on one end face of the rotor core 31 in the axial direction, and the plurality of buckle points 311 are evenly spaced along the circumference of the rotor core 31, and a buckle point 311 is arranged between two adjacent magnetic steels 32. Specifically, a plurality of grooves are arranged on the other end face of the rotor core 31 in the axial direction, and the plurality of grooves correspond to the positions of the plurality of buckle points 311 one by one. It can be understood that when the plurality of rotor cores 31 are superimposed on each other, the buckle point 311 of one rotor core 31 can be buckled in the groove of another rotor core 31 to form a self-buckle, so that the structure is firm and stable. At the same time, the magnetic steel 32 is embedded in the rotor core 31, which can reduce the loss of the central motor and improve the motor efficiency, and can also save costs. In this embodiment, the buckle point 311 is rectangular, and the groove is also rectangular. In other embodiments, the buckle point 311 and the groove may also be in other shapes such as a circle.

[0066] In this embodiment, multiple buckle points 311 are evenly spaced along the circumferential direction of the rotor core 3 and near the axis position, and correspondingly, multiple grooves are also arranged at the same position on the other end surface of the rotor core 31 to correspond thereto. Through the above arrangement, the structural stability of multiple rotor cores 31 can be ensured when they are stacked on each other. In other embodiments, the positions and numbers of the buckle points 311 and the grooves can also be changed according to different usage requirements.

[0067] In this embodiment, a certain air gap is provided between one end of the magnetic steel 32 and the rotor core 31 , and the magnetic leakage of the magnetic steel 32 can be reduced through the air gap. The shape and size of the air gap are not limited herein.

[0068] Alternatively, if Fig. 9 As shown, the rotor core 31 is evenly spaced along the circumferential direction and is provided with a plurality of circular through holes 312, and the plurality of circular through holes 312 extend along the axial direction of the rotor core 31. Specifically, two circular through holes 312 are provided between two adjacent magnetic steels 32. The circular through holes 312 can reduce the cogging torque of the motor, thereby improving the performance of the motor. As for the size of the circular through holes 312, there is no limitation. In other embodiments, the number of the circular through holes 312 can be appropriately increased or decreased according to different usage requirements.

[0069] In this embodiment, Fig. 9 As shown, the rotor core 31 is also provided with a plurality of through holes 313 arranged at intervals. The plurality of through holes 313 are arranged along the circumferential direction of the rotor core 31 and extend along the axial direction of the rotor core 31. The through holes 313 are provided at one end of the magnet 32 ​​away from the air gap. The magnet slot where each magnet 32 ​​is located is connected to two through holes 313. The through holes 313 can further reduce the magnetic leakage of the magnet 32 ​​and improve the service life of the motor.

[0070] This embodiment also provides an electric power-assisted bicycle, including the above-mentioned mid-mounted motor. The electric power-assisted bicycle has three usage modes: electric mode, riding mode and power-assisted mode. When the electric power-assisted bicycle is in electric mode, after the motor is powered on, the rotor assembly 3 drives the sun gear 4 to rotate, the sun gear 4 drives the double planetary gear 52 to rotate, and then drives the planetary frame 53 and the support frame 55 to rotate, the support frame 55 drives the pulley 61 to rotate through the first inner wheel 64 and the first roller 65 of the transmission assembly 6, the pulley 61 drives the output pulley 71 to rotate through the synchronous belt 62, at this time, the clutch assembly 7 is in a disengaged state, the second roller 73 and the third roller 74 will not transmit power, the second inner wheel 72 will not generate movement, and the output pulley 71 then drives the sprocket 10 to rotate, thereby being able to drive the wheel to rotate. When the electric power-assisted bicycle is in riding mode, the motor is not powered and the rotor assembly 3 does not rotate. At this time, the middle shaft 8 is rotated by pedaling the foot and the crank, and the middle shaft 8 drives the second inner core wheel 72 to rotate. At this time, the clutch assembly 7 is in a coupled state, and the second inner core wheel 72 drives the output pulley 71 to rotate through the second roller 73 and the third roller 74, and the output pulley 71 drives the pulley 61 to rotate through the synchronous belt 62. At this time, the transmission assembly 6 is in a disengaged state and cannot transmit power, so the planetary gear assembly 5 does not move. At the same time, the output pulley 71 can drive the sprocket 10 to rotate, thereby driving the wheel to rotate. When the electric power-assisted bicycle is in the power-assisted mode, the pedals are stepped on to rotate the middle shaft 8 through the crank, and the middle shaft 8 drives the second inner wheel 72 to rotate. At this time, the clutch assembly 7 is in a coupled state, and the second inner wheel 72 drives the output pulley 71 to rotate through the second roller 73 and the third roller 74. At this time, the controller 13 processes the torque of the middle shaft 8 collected by the detection element, and controls the motor to start and work through power distribution. The rotor assembly 3 drives the sun gear 4 to rotate, and then drives the double planetary gear 52 to rotate, driving the planetary carrier 53 and the support frame 55 to rotate. At this time, the transmission assembly 6 can transmit power, and the pulley 61 drives the output pulley 71 to rotate through the synchronous belt 62, and transmits power to the output pulley 71. In this mode, the pedals and the motor act on the output pulley 71 at the same time to drive the sprocket 10 to rotate, thereby driving the wheel to rotate, which can achieve the effect of saving effort.

[0071] Embodiment 2

[0072] The difference between this embodiment and the first embodiment is that Fig.10 and 11 As shown, the outer circumference of the first inner wheel 64 is also provided with a plurality of semi-arc grooves 642 at intervals, the first arc grooves 641 and the semi-arc grooves 642 are alternately arranged, and when the first roller 65 rolls in the first arc groove 641, the semi-arc grooves 642 can cooperate with the inner wall of the pulley 61 to ensure the free rolling of the first roller 65, thereby improving the transmission efficiency of the transmission assembly 6 and ensuring silent operation.

[0073] In this embodiment, a baffle 67 is used in the transmission assembly 6 to replace the first bearing 66. The first roller 65 is respectively in contact with the limiting step of the pulley 61 and the baffle 67 at both ends in the axial direction. The baffle 67 can limit the first roller 65 in the axial direction of the first inner wheel 64 to prevent the first roller 65 from coming out in the axial direction of the first inner wheel 64. By using the baffle 67 instead of the first bearing 66, the structure of the transmission assembly 6 can be simplified, ensuring a smoother operation.

[0074] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A mid-mounted motor, characterized in that: include: Housing (1); A stator (2), the stator (2) being fixedly connected to the casing (1); A rotor assembly (3), the rotor assembly (3) being coaxially and rotatably disposed inside the stator (2); A sun gear (4), the sun gear (4) being fixedly disposed through the rotor assembly (3) and rotatably connected to the casing (1); A planetary gear assembly (5), comprising an inner gear ring (51), a duplex planetary gear (52) meshing with the inner gear ring (51), and a planet carrier (53) connected to the duplex planetary gear (52), wherein the inner gear ring (51) is fixedly connected to the housing (1), the duplex planetary gear (52) is meshing with the sun gear (4), and the planet carrier (53) is rotationally connected to the sun gear (4) and is fixedly connected to the duplex planetary gear (52); A transmission assembly (6), the transmission assembly (6) comprising a pulley (61) and a synchronous belt (62) drivingly connected to the pulley (61), the pulley (61) being drivingly connected to the planet carrier (53); The transmission assembly (6) further comprises a first inner wheel (64) coaxially arranged inside the pulley (61), a plurality of first rollers (65) are evenly spaced between the first inner wheel (64) and the inner wall of the pulley (61) along the circumferential direction of the first inner wheel (64), and the first rollers (65) are capable of rolling between the first inner wheel (64) and the pulley (61); When the sun gear (4) rotates and drives the double planetary gear (52) to rotate, the transmission assembly (6) is in a coupled state, the first roller (65) can be pressed between the first inner core wheel (64) and the pulley (61), and can transmit power to the pulley (61); when the pulley (61) rotates, the transmission assembly (6) is in a disengaged state, and power cannot be transmitted between the first inner core wheel (64) and the pulley (61); A clutch assembly (7), the clutch assembly (7) being drivingly connected to the synchronous belt (62); A middle shaft (8), wherein the middle shaft (8) extends along the axial direction of the sun gear (4) and is connected to the clutch assembly (7).

2. The mid-mounted motor according to claim 1, characterized in that: The planetary gear assembly (5) further comprises a connecting pin (54) and a support frame (55); the connecting pin (54) is rotatably inserted into the double-linked planetary gear (52) and its two ends are respectively fixedly connected to the planet frame (53) and the support frame (55); the support frame (55) is connected to the pulley (61).

3. The mid-mounted motor according to claim 1, characterized in that: The central motor further comprises a first housing (9), the housing (1) and the inner gear ring (51) are respectively fixed on two sides of the first housing (9), and the planet carrier (53) and the central shaft (8) are both rotatably connected to the first housing (9).

4. The mid-mounted motor according to claim 1, characterized in that: The clutch assembly (7) comprises an output pulley (71) and a second inner wheel (72) coaxially arranged inside the output pulley (71); a plurality of second rollers (73) are evenly spaced between the second inner wheel (72) and the inner wall of the output pulley (71) along the circumferential direction of the second inner wheel (72); the second rollers (73) are capable of rolling between the second inner wheel (72) and the output pulley (71); the second inner wheel (72) is key-connected to the center shaft (8); the output pulley (71) is transmission-connected to the synchronous belt (62) and rotationally connected to the center shaft (8).

5. The mid-mounted motor according to claim 4, characterized in that: A plurality of third rollers (74) are evenly spaced apart between the second inner wheel (72) and the inner wall of the output pulley (71) along the circumferential direction of the second inner wheel (72); the third rollers (74) are capable of rolling between the second inner wheel (72) and the output pulley (71); the third rollers (74) and the second rollers (73) are alternately arranged and the diameter of the third rollers (74) is smaller than the diameter of the second rollers (73).

6. The mid-mounted motor according to claim 5, characterized in that: The clutch assembly (7) also includes a retaining frame (75), which is coaxially arranged between the second inner wheel (72) and the output pulley (71) and can abut against the plurality of second rollers (73) and the plurality of third rollers (74) along the axial direction of the second inner wheel (72).

7. The mid-mounted motor according to any one of claims 1 to 6, characterized in that: The rotor assembly (3) comprises a rotor core (31) and a plurality of magnetic steels (32) embedded in the rotor core (31), wherein the plurality of magnetic steels (32) are evenly spaced along the circumference of the rotor core (31); a plurality of buckling points (311) are arranged on one end face of the rotor core (31) in the axial direction, wherein the plurality of buckling points (311) are evenly spaced along the circumference of the rotor core (31), wherein one buckling point (311) is arranged between two adjacent magnetic steels (32); and a plurality of grooves are arranged on the other end face of the rotor core (31) in the axial direction, wherein the plurality of grooves correspond one to one to the positions of the plurality of buckling points (311).

8. The mid-mounted motor according to claim 7, characterized in that: The rotor core (31) is provided with a plurality of circular through holes (312) at even intervals along the circumferential direction, and the plurality of circular through holes (312) all extend along the axial direction of the rotor core (31).

9. The mid-mounted motor according to any one of claims 1 to 8, characterized in that: The central motor further comprises a detection element, the detection element is fixedly connected to the central shaft (8), and the detection element is used to detect the torque of the central shaft (8).

10. An electric power-assisted bicycle, characterized in that: Including the mid-mounted motor as described in any one of claims 1-9.

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