Middle motor and power-assisted bicycle

Abstract

The utility model relates to the technical field of power devices, and discloses a middle motor and a power-assisted bicycle. The middle motor comprises a motor shaft system, a second shaft system, a third shaft system and an output shaft system which are parallel to one another and are sequentially in transmission connection through gears; the output shaft system comprises an output shaft assembly, an output interface and a three-stage output gear, the output interface and the three-stage output gear are arranged on the output shaft assembly at intervals, the output interface is connected with the crankset, the three-stage output gear is in transmission connection with the three-shaft system, and the shaft diameter of the part, located between the three-stage output gear and the output interface, of the output shaft assembly is D1; the shaft diameter of the part located on the side, away from the output interface, of the third-stage output gear is D2, and D1 is larger than D2; the three-shaft system comprises a three-shaft assembly and a second-stage output gear, the second-stage output gear is arranged on the three-shaft assembly and is in transmission connection with the two-shaft system, and the second-stage output gear is arranged on the side, away from the output interface, of the third-stage output gear in the axial direction. The mid-motor has a high maximum output torque on the basis of ensuring a small axial projection area and a small axial size.

Description

TECHNICAL FIELD

[0001] The utility model relates to power device technical field especially relates to a middle -position motor and power -assisted bicycle. BACKGROUND

[0002] With the popularization of green travel concept and the pursuit of healthy life of consumer, power -assisted bicycle market is also gradually expanding. Among them, the middle -position motor is the core component of power -assisted bicycle, and it provides the power output that coordinates with human force through the real -time detection of the sensor of the pedaling strength of the rider.

[0003] The middle -position motor is always developing towards compactness, high output torque, and the three -stage middle -position motor has the advantages of more stable torque output and more compact structure compared with the two -stage middle -position motor, and is widely used. However, the existing three -stage transmission middle -position motor, based on the arrangement of the transmission structure of each stage, causes the overall projection area and / or axial dimension in the output shaft system axial direction to be larger, which is difficult to meet the development trend of compactness, and if the size of the transmission gear is directly reduced on the basis of the original arrangement to reduce its projection area in the axial direction, the maximum output torque will be reduced.

[0004] Therefore, there is an urgent need for a middle -position motor and power -assisted bicycle to solve the above technical problems. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a middle -position motor and power -assisted bicycle, which has a higher maximum output torque on the basis of ensuring a smaller axial projection area and axial dimension.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] The middle -position motor comprises a motor shaft system, a two -shaft system, a three -shaft system and an output shaft system which are connected in sequence through gear transmission and are parallel to each other.

[0008] The output shaft system comprises an output shaft assembly, an output interface and a three -stage output gear, the output interface and the three -stage output gear are connected with the output shaft assembly and are arranged at intervals, the output interface is used for connecting with a sprocket, the three -stage output gear is in transmission connection with the three -shaft system, the shaft diameter of the part of the output shaft assembly between the three -stage output gear and the output interface is D1, the shaft diameter of the part of the output shaft assembly on the side of the three -stage output gear away from the output interface is D2, and D1>D2.

[0009] The three -shaft system comprises a three -shaft assembly and a two -stage output gear, the two -stage output gear is arranged on the three -shaft assembly and is in transmission connection with the two -shaft system, and along the axial direction, the two -stage output gear is arranged on the side of the three -stage output gear away from the output interface.

[0010] As an optional solution, the motor shaft system comprises a motor shaft assembly and a first-stage input gear arranged on the motor shaft assembly, the second shaft system comprises a second shaft assembly and a first-stage output gear arranged on the second shaft assembly, and the first-stage input gear is engaged with the first-stage output gear.

[0011] The first-stage input gear and the first-stage output gear are located on the side of the second-stage output gear facing the third-stage output gear and at least partially overlap the third-stage output gear in the axial direction.

[0012] As an optional solution, a line defined between the center of the axial projection of the motor shaft system and the center of the axial projection of the output shaft system is defined as a first reference line, and the center of the axial projection of the second shaft system and the center of the axial projection of the third shaft system are both arranged on the first side of the first reference line.

[0013] As an optional solution, a straight line passing through the center of the axial projection of the motor shaft system and perpendicular to the first reference line is defined as a second reference line, the axial projection of the second shaft system is at least partially located on one side of the second reference line, and the axial projection of the third shaft system is at least partially located on the other side of the second reference line.

[0014] As an optional solution, the in-wheel motor further comprises an electric control assembly, and at least part of the electric control assembly is arranged on the second side of the first reference line.

[0015] As an optional solution, the axial projection of the second shaft system partially overlaps the axial projection of the motor shaft system; and / or

[0016] The axial projection of the third shaft system partially overlaps the axial projection of the motor shaft system; and / or

[0017] The axial projection of the output shaft system partially overlaps the axial projection of the motor shaft system.

[0018] As an optional solution, the center of the axial projection of the motor shaft system is defined as O, the center of the axial projection of the second shaft system is defined as A, the center of the axial projection of the third shaft system is defined as B, and the center of the axial projection of the output shaft system is defined as C, wherein OC>OA; OC>AB; and OC>BC.

[0019] As an optional solution, the center of the axial projection of the motor shaft system is defined as O, the center of the axial projection of the second shaft system is defined as A, the center of the axial projection of the third shaft system is defined as B, and the center of the axial projection of the output shaft system is defined as C, wherein ∠OCA<90°, ∠OCB<90°, and ∠ACB<90°.

[0020] As an optional solution, the middle motor further comprises a shell, the motor shaft system, the second shaft system and the third shaft system are arranged in the shell, and two ends of the output shaft assembly and the output interface are arranged outside the shell.

[0021] A power-assisted bicycle comprises a frame and the middle motor.

[0022] The power-assisted bicycle has the beneficial effects that:

[0023] The middle motor has the beneficial effects that: the output interface has a large transmission external load, the shaft diameter D1 of the output shaft assembly on the side of the three-stage output gear where the output interface is arranged is larger than the shaft diameter D2 of the three-stage output gear on the side where the output interface is not arranged, the second-stage output gear on the three-shaft assembly is arranged on the side of the three-stage output gear away from the output interface, the second-stage output gear is opposite to the part of the output shaft assembly with a smaller shaft diameter, the stress of the entire output shaft assembly can meet the actual demand, the diameter of the second-stage output gear can be increased as much as possible, that is, the transmission ratio between the second shaft system and the third shaft system is increased, and the maximum output torque of the entire middle motor is increased, the detection components are arranged on the part of the three-stage output gear away from the output interface, the axial dimension of this part cannot be further reduced, the diameter of the second-stage output gear is large enough, the scheme does not need to arrange an empty section for avoiding the second-stage output gear between the output interface and the three-stage output gear, the axial dimension of the entire output shaft assembly is small, and the axial dimension of the entire middle motor is reduced.

[0024] The power-assisted bicycle has the beneficial effects that: the maximum output torque is high on the basis of a small axial projection area and / or axial dimension of the middle motor. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the middle motor provided in the specific embodiment of the utility model;

[0026] Figure 2 is a schematic diagram of the middle motor hidden in the shell provided in the specific embodiment of the utility model;

[0027] Figure 3 is a matching schematic diagram of the shaft systems provided in the specific embodiment of the utility model;

[0028] Figure 4is the schematic diagram of the second shaft arrangement provided by the embodiment of the utility model;

[0029] Figure 5 is the schematic diagram of the third shaft arrangement provided by the embodiment of the utility model;

[0030] Figure 6 is the schematic diagram of the fourth shaft arrangement provided by the embodiment of the utility model;

[0031] Figure 7 is the schematic diagram of the fifth shaft arrangement provided by the embodiment of the utility model;

[0032] Figure 8 is the schematic diagram of the sixth shaft arrangement provided by the embodiment of the utility model;

[0033] Figure 9 is the schematic diagram of the seventh shaft arrangement provided by the embodiment of the utility model;

[0034] Figure 10 is the schematic diagram of the eighth shaft arrangement provided by the embodiment of the utility model;

[0035] Figure 11 is the schematic diagram of the ninth shaft arrangement provided by the embodiment of the utility model;

[0036] Figure 12 is the top view of the structure in Figure 3 ;

[0037] Figure 13 is the side view of the structure in Figure 3 .

[0038] In the figure:

[0039] 10, motor shaft system;11, motor shaft assembly;111, motor shaft body;112, first bearing;12, primary input gear;13, motor;

[0040] 20, two-shaft system;21, two-shaft assembly;211, two-shaft body;212, second bearing;22, primary output gear;23, secondary input gear;

[0041] 30, three-shaft system;31, three-shaft assembly;311, three-shaft body;312, third bearing;32, secondary output gear;33, tertiary input gear;

[0042] 40, output shaft system;41, output shaft assembly;411, output shaft body;412, fourth bearing;42, output interface;43, tertiary output gear;

[0043] 50, electric control assembly;

[0044] 60, housing; 61, upper housing; 62, lower housing; 63, rear housing;

[0045] 101, first reference line; 102, second reference line. DETAILED DESCRIPTION

[0046] The utility model will be described in further detail below in combination with the drawings and examples. It can be understood that the specific examples described herein are only used to explain the utility model, and not to limit the utility model. In addition, it should be noted that only the parts related to the utility model are shown in the drawings for ease of description, not all the structures.

[0047] In the description of the utility model, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship of two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0048] In the utility model, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0049] In the description of the embodiment, the terms "upper", "lower", "right", etc. orientation or position relationship is based on the orientation or position relationship shown in the drawings, only for the convenience of description and simplification of operation, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second" are only used to distinguish in description, and have no special meaning.

[0050] The embodiment provides a middle motor, and the middle motor is used for power-assisted bicycle as an example.

[0051] As Figure 1 and Figure 2As shown in the figure, the mid-drive motor comprises a housing 60, a motor shaft system 10, a two-shaft system 20, a three-shaft system 30 and an output shaft system 40, wherein the motor shaft system 10, the two-shaft system 20, the three-shaft system 30 and part of the output shaft system 40 are arranged in the housing 60, and part of the output shaft system 40 is arranged outside the housing 60 to facilitate coupling with the structure of the assist bicycle. Optionally, the housing 60 comprises an upper shell 61, a lower shell 62 and a rear shell 63, the upper shell 61 and the lower shell 62 are coupled together, and the rear shell 63 is connected to the side of the lower shell 62 away from the upper shell 61, and the three shells together form a space for accommodating the above-mentioned structure. The upper shell 61 and the lower shell 62 can be connected by bolts or other fasteners, and the lower shell 62 and the rear shell 63 can be fixed by thread connection, fastener connection or other methods. As shown in the figure, Figure 2 As shown in the figure, the motor shaft system 10, the two-shaft system 20, the three-shaft system 30 and the output shaft system 40 are parallel to each other and are sequentially connected by gear transmission, and the entire mid-drive motor forms a three-stage transmission structure, thereby having the advantages of more stable torque output and more compact structure.

[0052] Specifically, as shown in the figure, Figure 2 The motor shaft system 10 comprises a motor 13, a motor shaft assembly 11 and a first-stage input gear 12, wherein the motor shaft assembly 11 is connected to the output shaft of the motor 13 and is supported on the housing 60. In this embodiment, the motor shaft assembly 11 comprises a motor shaft body 111 and at least two first bearings 112 mounted on the motor shaft body 111, the first-stage output gear 12 is mounted on the motor shaft body 111, and the first bearings 112 are connected to the housing 60, so that the motor shaft body 111 and the first-stage input gear 12 can rotate smoothly under the drive of the motor 13.

[0053] As shown in the figure, Figure 2 The two-shaft system 20 comprises a two-shaft assembly 21, a first-stage output gear 22 and a second-stage input gear 23, wherein the two-shaft assembly 21 comprises a two-shaft body 211 and at least two second bearings 212 arranged on the two-shaft body 211, the first-stage output gear 22 and the second-stage input gear 23 are arranged on the two-shaft body 211, the first-stage output gear 22 is engaged with the first-stage input gear 12, and a first-stage transmission is formed between the first-stage input gear 12 and the first-stage output gear 22. The at least two second bearings 212 are connected to the housing 60, so that the two-shaft body 211, the first-stage output gear 22 and the second-stage input gear 23 can rotate smoothly and synchronously relative to the housing 60. Optionally, in this embodiment, the first-stage output gear 22 and the second-stage input gear 23 are in a split structure, and the diameter of the second-stage input gear 23 is smaller than that of the first-stage output gear 22. In other embodiments, the first-stage output gear 22 and the second-stage input gear 23 can also be arranged in an integrally formed structure.

[0054] As shown in the figure, Figure 2As shown, the three-axis system 30 comprises a three-axis assembly 31, a secondary output gear 32 and a tertiary input gear 33, wherein the three-axis assembly 31 comprises a three-axis body 311 and at least two third bearings 312 arranged on the three-axis body 311, the secondary output gear 32 and the tertiary input gear 33 are both arranged on the three-axis body 311, the secondary output gear 32 is engaged with the secondary input gear 23, thereby forming a secondary transmission. The at least two third bearings 312 are connected with the housing 60, thereby enabling the three-axis body 311, the secondary output gear 32 and the tertiary input gear 33 to rotate stably and synchronously relative to the housing 60. Optionally, in the embodiment, the secondary output gear 32 and the tertiary input gear 33 are both in a split structure, and the diameter of the tertiary input gear 33 is smaller than that of the secondary output gear 32. In other embodiments, the secondary output gear 32 and the tertiary input gear 33 can also be arranged in an integrally formed structure.

[0055] As shown, Figure 2 The output shaft system 40 comprises an output shaft assembly 41, an output interface 42 and a tertiary output gear 43, wherein the output shaft assembly 41 comprises an output shaft body 411 and at least two fourth bearings 412 arranged on the output shaft body 411, and the two ends of the output shaft body 411 are respectively provided with a matching part, and the two matching parts are used to connect with the pedal crank of the power-assisted bicycle. Optionally, the matching part can be a spline. The output interface 42 is connected with the output shaft body 411 and is used to connect with the sprocket of the power-assisted bicycle (the sprocket is matched with the chain transmission of the power-assisted bicycle). The tertiary output gear 43 is arranged on the output shaft body 411 and is engaged with the tertiary input gear 33, thereby forming a tertiary transmission between the tertiary input gear 33 and the tertiary output gear 43. The at least two fourth bearings 412 are respectively connected with the housing 60, thereby enabling the output shaft body 411, the output interface 42 and the tertiary output gear 43 to rotate synchronously relative to the housing 60. In some embodiments, the tertiary output gear 43 and the output interface 42 can also be arranged in an integrally formed structure.

[0056] It should be noted that in the embodiment, in the transmission structure of the same level, the diameter of the input gear is smaller than that of the output gear, thereby achieving the effect of speed reduction and torque increase. Of course, in some embodiments, the diameter of the input gear in the transmission structure of the same level can be arranged to be the same as that of the output gear. In addition, the middle motor further comprises two clutches, one of which is a pedaling clutch, which is used to disconnect the transmission when manual pedaling does not require the assistance of the middle motor, so that the above-mentioned tertiary transmission structure is no longer transmitted, thereby reducing the pedaling resistance. The other clutch is a power-assisted clutch, which is used to disconnect the transmission when the motor rotates too fast to avoid the situation that the pedal drives the foot movement. It can be understood that at least one of the above-mentioned two clutches is arranged on the output shaft system 40, and the other clutch can be arranged on any one of the two-axis system 20, the three-axis system 30 and the output shaft system 40.

[0057] As shown in Figure 2 and Figure 3 , along the axial direction, the motor 13 and the output interface 42 are arranged in axial opposition, the three-stage transmission structure is arranged between the motor 13 and the output interface 42, so that the axial projection of the two-axis system 20 partially overlaps the axial projection of the motor axis system 10, the axial projection of the three-axis system 30 partially overlaps the axial projection of the motor axis system 10, and the axial projection of the output shaft system 40 partially overlaps the axial projection of the motor axis system 10. In this way, on the basis of ensuring normal transmission, the arrangement of the four shaft systems is more compact, thereby reducing the overall projection area of the middle motor in the axial direction. It can be understood that in other embodiments, among the axial projection of the two-axis system 20, the axial projection of the three-axis system 30, and the axial projection of the output shaft system 40, only one or two can partially overlap the axial projection of the motor axis system 10.

[0058] As shown in Figure 3 , the line defined between the center of the axial projection of the motor axis system 10 and the center of the axial projection of the output shaft system 40 is the first reference line 101, and the center of the axial projection of the two-axis system 20 and the center of the axial projection of the three-axis system 30 are both arranged on the first side of the first reference line 101. The straight line passing through the center of the axial projection of the motor axis system 10 and perpendicular to the first reference line 101 is the second reference line 102, and the axial projection of the two-axis system 20 is at least partially located on one side of the second reference line 102, and the axial projection of the three-axis system 30 is at least partially located on the other side of the second reference line 102. In this way, on the one hand, the four shaft systems are more compact in structure on the basis of ensuring normal transmission, i.e., the axial projection area is smaller; on the other hand, it is beneficial to ensure that the width-to-length ratio of the circumscribed rectangle of the axial projection of the four shaft systems is closer to the golden ratio, and thus the width-to-length ratio of the circumscribed rectangle of the overall axial projection of the housing 60 is closer to the golden ratio, thereby improving the aesthetics of the entire middle motor. In the present embodiment, the center of the axial projection of the two-axis system 20 and the center of the axial projection of the three-axis system 30 are respectively located on the two sides of the second reference line 102.

[0059] As shown in Figure 3 , the center of the axial projection of the motor axis system 10 is O, the center of the axial projection of the two-axis system 20 is A, the center of the axial projection of the three-axis system 30 is B, and the center of the axial projection of the output shaft system 40 is C, wherein OC>OA; OC>AB; OC>BC. ∠OCA<90°, ∠OCB<90°, ∠ACB<90°. In this way, not only is the arrangement of the four shaft systems compact, i.e., the axial projection area is smaller; but also it is beneficial to ensure that the width-to-length ratio of the circumscribed rectangle of the axial projection of the four shaft systems is closer to the golden ratio.

[0060] In the present embodiment, a method for manufacturing the middle motor is also providedFigures 4-11 The schematic diagram of the eight axial arrangement positions shown is calculated to ensure the same transmission ratio (i.e. the same output torque) under the condition that Figure 3 The scheme shown has the smallest axial projection area.

[0061] As Figure 12 As shown, the middle motor further comprises an electric control assembly 50, at least part of the electric control assembly 50 is arranged on the second side of the first reference line 101. In this embodiment, the second shaft system 20 and the third shaft system 30 are located on one side of the first reference line 101, and most of the electric control assembly 50 is located on the other side of the first reference line 101, and in the axial direction, the electric control assembly 50 is opposite to each level of transmission structure. Such arrangement makes the internal structure of the middle motor compact. It can be understood that the electric control assembly 50 comprises components arranged near the motor shaft body 111 and used for collecting information such as rotor angle and rotation speed of the motor 13, components arranged near the output shaft body 411 and used for detecting information such as output torque, pedal stepping frequency, etc., and circuit boards for processing the above information, etc. The above electric control assembly 50 is of existing structure, and the principle thereof will not be further described herein.

[0062] As Figure 13 As shown, the shaft diameter of the part of the output shaft assembly 41 (including the output shaft body 411 and the fourth bearing 412 or other components thereon) between the third level output gear 43 and the output interface 42 is D1, the shaft diameter of the part of the output shaft assembly 41 on the side of the third level output gear 43 away from the output interface 42 is D2, and D1>D2; in the axial direction, the second level output gear 32 is arranged on the side of the third level output gear 43 away from the output interface 42.

[0063] Due to the large transmission external load of the output interface 42 and the gear plate connected thereto, the shaft diameter D1 of the output shaft assembly 41 on the side where the three-stage output gear 43 is provided with the output interface 42 is set to be larger than the shaft diameter D2 of the side where the three-stage output gear 43 is not provided with the output interface 42, and the two-stage output gear 32 on the three-shaft assembly 31 is arranged on the side of the three-stage output gear 43 away from the output interface 42, that is, the two-stage output gear 32 is opposite to the smaller part of the output shaft assembly 41, so that the stress of the entire output shaft assembly 41 can meet the actual demand. Secondly, on the basis of ensuring a smaller axial projection area (that is, when the distance between the shafts is constant), the diameter of the two-stage output gear 32 can be increased as much as possible, that is, the transmission ratio between the two-shaft system 20 and the three-shaft system 30 is increased, thereby increasing the maximum output torque of the entire mid-drive motor. In addition, since the mid-drive motor is installed with detection components on the part of the three-stage output gear 43 away from the output interface 42, the axial size of this part cannot be further reduced. On the basis of ensuring a large enough maximum output torque (that is, ensuring that the diameter of the two-stage output gear 32 is large enough), the present scheme does not need to set an empty section for avoiding the two-stage output gear 32 between the output interface 42 and the three-stage output gear 43, thereby making the axial size of the output shaft assembly 41 smaller, and thereby facilitating the reduction of the axial size of the entire mid-drive motor.

[0064] As shown in Figure 13 The first-stage input gear 12 and the first-stage output gear 22 are both located on the side of the two-stage output gear 32 facing the three-stage output gear 43, and at least partially overlap the three-stage output gear 43 in the axial direction, that is, the first-stage transmission structure and the three-stage transmission structure are arranged opposite to each other, thereby reducing the axial size of the entire mid-drive motor, and meeting the compact development of the mid-drive motor.

[0065] The embodiment also provides a power-assisted bicycle, which comprises a frame and a mid-drive motor, the mid-drive motor is installed on the frame, the two pedal cranks of the frame are respectively matched with the splines at both ends of the output shaft body 411, and the gear plate of the frame is connected with the output interface 42. The power-assisted bicycle of the embodiment can ensure a high maximum output torque on the basis of ensuring a small axial projection area and / or axial size of the mid-drive motor.

[0066] Obviously, the above embodiments of the utility model are only examples for clearly illustrating the utility model, and are not a limitation on the embodiments of the utility model. For ordinary skilled in the art, according to the idea of the utility model, the specific embodiments and application range can be changed, and the content of the specification should not be understood as a limitation on the utility model. Any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model claims.

Claims

1. An electric motor, characterized in that The motor shaft system (10), the two-shaft system (20), the three-shaft system (30) and the output shaft system (40) are parallel to each other and are sequentially connected through gear transmission; The output shaft system (40) comprises an output shaft assembly (41), an output interface (42) and a three-stage output gear (43), the output interface (42) and the three-stage output gear (43) are both connected with the output shaft assembly (41) and are arranged at intervals, the output interface (42) is used for being connected with a toothed disc, the three-stage output gear (43) is in transmission connection with the three-shaft system (30), the shaft diameter of the part of the output shaft assembly (41) between the three-stage output gear (43) and the output interface (42) is D1, the shaft diameter of the part of the output shaft assembly (41) on the side of the three-stage output gear (43) away from the output interface (42) is D2, and D1>D2; The three-shaft system (30) comprises a three-shaft assembly (31) and a two-stage output gear (32), the two-stage output gear (32) is arranged on the three-shaft assembly (31) and is in transmission connection with the two-shaft system (20), and in the axial direction, the two-stage output gear (32) is arranged on the side of the three-stage output gear (43) away from the output interface (42).

2. The line start motor of claim 1, wherein, The motor shaft system (10) comprises a motor shaft assembly (11) and a first-stage input gear (12) arranged on the motor shaft assembly (11), the two-shaft system (20) comprises a two-shaft assembly (21) and a first-stage output gear (22) arranged on the two-shaft assembly (21), and the first-stage input gear (12) is in meshing connection with the first-stage output gear (22); The first-stage input gear (12) and the first-stage output gear (22) are both located on the side of the two-stage output gear (32) facing the three-stage output gear (43) and at least partially overlap the three-stage output gear (43) in the axial direction.

3. The motor as set forth in claim 1, wherein A line defined between the center of the axial projection of the motor shaft system (10) and the center of the axial projection of the output shaft system (40) is defined as a first reference line (101), and the center of the axial projection of the two-shaft system (20) and the center of the axial projection of the three-shaft system (30) are both arranged on the first side of the first reference line (101).

4. The motor as claimed in claim 3, wherein A straight line passing through the center of the axial projection of the motor shaft system (10) and being perpendicular to the first reference line (101) is defined as a second reference line (102), the axial projection of the two-shaft system (20) is at least partially located on one side of the second reference line (102), and the axial projection of the three-shaft system (30) is at least partially located on the other side of the second reference line (102).

5. The motor as set forth in claim 3, wherein The middle motor further comprises an electric control assembly (50), and at least part of the electric control assembly (50) is arranged on the second side of the first reference line (101).

6. The motor as claimed in claim 1, wherein The axial projection of the two-shaft system (20) partially overlaps the axial projection of the motor shaft system (10); and / or The axial projection of the three-shaft system (30) partially overlaps the axial projection of the motor shaft system (10); and / or The axial projection of the output shaft system (40) partially overlaps the axial projection of the motor shaft system (10).

7. The motor as claimed in claim 1, wherein The center of the axial projection of the motor shaft system (10) is defined as O, the center of the axial projection of the two-shaft system (20) is defined as A, the center of the axial projection of the three-shaft system (30) is defined as B, and the center of the axial projection of the output shaft system (40) is defined as C, wherein OC>OA; OC>AB; and OC>BC.

8. The motor as claimed in claim 1, wherein The center of the axial projection of the motor shaft system (10) is defined as O, the center of the axial projection of the two-shaft system (20) is defined as A, the center of the axial projection of the three-shaft system (30) is defined as B, and the center of the axial projection of the output shaft system (40) is defined as C, wherein ∠OCA<90°, ∠OCB<90°, and ∠ACB<90°.

9. An IPM as set forth in any of claims 1-8, characterized in that, The in-wheel motor further comprises a housing (60), the motor shaft system (10), the two-shaft system (20), and the three-shaft system (30) are arranged in the housing (60), and both ends of the output shaft assembly (41) and the output interface (42) are arranged outside the housing (60).

10. A power assisted bicycle characterised in that, A vehicle comprising a frame and an in-wheel motor according to any one of claims 1-9.

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