Hidden type middle motor structure

Abstract

The utility model discloses a hidden type middle motor structure which comprises a shell, a motor used for providing driving force and a harmonic gear in transmission connection with an output shaft of the motor, the harmonic gear comprises a flexible gear, a rigid gear and a wave generator, the wave generator is installed on a middle shaft of a bicycle frame in an inserted mode, and the wave generator comprises a cam and a flexible bearing. An inner ring of the flexible bearing is arranged on the cam in a sleeving mode, teeth are arranged on the outer edge of the opening portion of the flexible gear, teeth are arranged on the inner ring of the rigid gear, when the wave generator is installed in the flexible gear, the section of the flexible gear becomes oval through elastic deformation, and the teeth of the flexible gear and the teeth of the rigid gear are meshed in and / or meshed out. According to the built-in motor, a long battery used by a common built-in motor can be provided, the hidden effect that the motor is not exposed is achieved, and a larger creation space is provided for a frame designer in the innovative design of the modeling of an electric bicycle.

Description

Technical Field

[0001] The utility model relates to the technical field of electric bicycles, in particular to a structure of a hidden mid-motor. Background Art

[0002] At present, electric bicycles are not only used as means of transportation, but also favored by a large number of cycling enthusiasts as sports tools. Electric bicycles are roughly divided into the rear-wheel hub motor type and the mid-motor type. Mid-motor bicycles have a stable center of gravity and a strong sense of riding security. Therefore, most sports and entertainment electric bicycles adopt the mid-motor type. Due to the fundamental attributes of sports and entertainment of mid-motor electric bicycles, it is required that the overall appearance of the bicycle is beautiful and the space occupied by the motor in the whole vehicle should not be too large.

[0003] To meet the above requirements, the mid-motor has evolved from the initial large-volume motor-frame integrated type to the relatively small-volume motor-frame split type. Whether it is the motor-frame integrated type or the split type, the relative positional relationship of the motor shaft, the reducer shaft and the main shaft is in a parallel state, and both the motor and the reducer are externally mounted on the frame, occupying a large space of the bicycle. How to overcome the deficiencies in the prior art and provide a hidden mid-motor and an electric bicycle equipped with the hidden mid-motor is a problem that plagues the current industry. There are the following solutions in the current industry. The motor shaft and the reducer shaft are coaxially designed to be perpendicular to the bicycle main shaft, which can greatly reduce the radial dimension and also achieve the effect of placing it in the inclined beam of the frame, realizing the hidden effect of the motor not being exposed.

[0004] The advantage of the existing solution is that the motor can be placed in the inclined beam of the frame, realizing the hidden effect of the motor not being exposed. It gives the frame designer more creative space in the innovative design of the electric bicycle shape. However, the biggest drawback of this solution is that since the motor is placed in the inclined beam of the frame, it occupies the space originally used to prevent the battery in the down tube, resulting in a relatively low cruising range of the whole vehicle compared with ordinary mid-motors, bringing a bad experience to consumers.

[0005] Therefore, how to solve the deficiencies existing in the above prior art has become the subject to be studied and solved in this application. Content of the Utility Model

[0006] In view of this, the purpose of the utility model is to provide a structure of a hidden mid-motor.

[0007] To achieve the above purpose, the technical solution adopted by the utility model is:

[0008] A structure of a hidden mid-drive motor, comprising a housing, a motor for providing driving force, and a harmonic gear transmissionally connected to the output shaft of the motor. The harmonic gear includes a flexspline, a rigid spline, and a wave generator. The wave generator is inserted into the bottom bracket of the bicycle frame. The wave generator includes a cam and a flexible bearing. The inner ring of the flexible bearing is sleeved on the cam. The outer edge of the opening of the flexspline has teeth, and the inner ring of the rigid spline has teeth. When the wave generator is inserted into the flexspline, the cross-section of the flexspline becomes oval through elastic deformation, and the teeth of the flexspline and the teeth of the rigid spline engage and / or disengage.

[0009] Further, the teeth of the flexspline at both ends of the major axis of the wave generator engage with the teeth of the rigid spline, the teeth of the flexspline at both ends of the minor axis of the wave generator disengage from the teeth of the rigid spline, and the teeth of the flexspline between the major axis and the minor axis of the wave generator are in a transitional state of engaging and disengaging with the teeth of the rigid spline.

[0010] Further, a rotor is sleeved on the bottom bracket. The rotor is connected to the output shaft of the motor. A stator is sleeved on the rotor. The rotor is electromagnetically connected to the stator. A first clutch is provided between the rotor and the wave generator.

[0011] Further, it further includes a chainring support. The driven end of the harmonic gear is connected to the chainring through the chainring support. A bearing assembly for supporting and positioning the chainring support is provided between the chainring support and the housing.

[0012] Further, the bottom bracket is connected to the chainring support through a second clutch.

[0013] Further, the flexspline is a thin-walled gear.

[0014] Further, the inner diameter of the flexspline is smaller than the major axis diameter of the wave generator.

[0015] Further, the wave generator adopts a mechanical wave generator with a rolling bearing.

[0016] The present application also provides an assisted bicycle, comprising a down tube and a battery pack. The structure of the hidden mid-drive motor and the battery pack are both installed in the down tube.

[0017] Compared with the prior art, the advantages of the present utility model are as follows: The harmonic gear has a high load-carrying capacity. In harmonic drive, the tooth-to-tooth meshing is surface contact, and with a relatively large number of simultaneously meshing teeth, the load per unit area is small, and the load-carrying capacity is higher than other drive forms. When obtaining the same reduction ratio, the harmonic gear is small in size and light in weight. At the same time, the harmonic gear drive has high efficiency, long service life, smooth transmission, no impact, no noise, and high motion accuracy. This application can not only have the long battery used in ordinary mid-mounted motors but also achieve the hidden effect of the motor not being exposed, providing a greater creative space for the innovative design of the frame designer in the styling of electric bicycles. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Attached Figure 1 is a schematic structural diagram of an embodiment of this application;

[0020] Attached Figure 2 is an assembly schematic diagram of an embodiment of this application.

[0021] The reference numerals and components involved in the drawings are described as follows:

[0022] 1. Housing; 2. Motor output shaft; 3. Flexspline; 4. Rigid spline; 5. Wave generator; 6. Central shaft; 7. Rotor; 8. Stator; 9. First clutch; 10. Chainring support; 11. Harmonic gear; 12. Second clutch. Detailed Embodiments

[0023] The following will clearly and completely describe the technical solutions of the present utility model through specific embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0024] See attached Figure 1 and attached Figure 2As shown in the figure, the structure of a hidden mid-motor of the present application includes a housing 1, a motor for providing driving force, and a harmonic gear 11 that is drivingly connected to the output shaft 2 of the motor. The harmonic gear 11 includes a flexspline 3, a rigid ring 4, and a wave generator 5. The wave generator 5 is inserted into a bottom bracket 6 on a bicycle frame. The wave generator 5 adopts a mechanical wave generator with a rolling bearing and is composed of a cam and a flexible bearing. The flexible bearing is a thin-walled ball bearing, that is, a thin-walled ball bearing is installed on the outer edge of the cam. The inner ring of the thin-walled ball bearing is fixed to the cam, and the elastic deformation of the outer ring lining is realized through the interaction between the balls and the cam. The flexspline 3 is a thin-walled cup-shaped metal flexible component with teeth on the outer edge of the opening part. Its cross-section is circular when not assembled. The bottom of the cup-shaped part of the flexspline 3 is called a diaphragm part, and the diaphragm part is usually used as the output end. The inner ring of the rigid ring 4 has teeth. The flexspline 3 is a thin-walled gear that can generate large elastic deformation. The inner hole diameter of the flexspline 3 is slightly smaller than the major axis diameter of the wave generator 5. The wave generator 5 is a component that causes the flexspline 3 to generate controllable elastic deformation. When the wave generator 5 is inserted into the flexspline 3, it forces the cross-section of the flexspline 3 to change from the original circular shape to an elliptical shape. The teeth near both ends of the major axis of the wave generator 5 are fully engaged with the teeth of the rigid ring 4, and the teeth near both ends of the minor axis of the wave generator 5 are completely disengaged from the rigid ring 4. The teeth of the flexspline 3 between the major axis and the minor axis of the wave generator 5 and the teeth in other sections are in a transitional state of engagement and disengagement with the teeth of the rigid ring 4. When the wave generator 5 rotates continuously, the deformation of the flexspline 3 changes continuously, causing the engagement state between the flexspline 3 and the rigid ring 4 to also change continuously, going through the processes of engagement, meshing, disengagement, separation, and re-engagement in a cycle, thereby realizing the slow rotation of the flexspline 3 relative to the rigid ring 4 in the opposite direction of the wave generator 5.

[0025] Preferably, as shown in the attached Figure 1 figure, a rotor 7 is sleeved on the bottom bracket 6 in this embodiment. The rotor 7 is connected to the output shaft 2 of the motor. A stator 8 is sleeved on the rotor 7, and there is an electromagnetic connection between the rotor 7 and the stator 8. A first clutch 9 is provided between the rotor 7 and the wave generator 5.

[0026] Preferably, as shown in the attached Figure 1 figure, this embodiment also includes a chainring support 10. The driven end of the harmonic gear 11 is connected to a chainring through the chainring support 10. A bearing assembly for supporting and positioning the chainring support is provided between the chainring support 10 and the housing 1. The chainring support 10 is connected to the bottom bracket 6 through a second clutch 12. When the present application works, the rigid ring 4 is fixed, and the motor drives the wave generator 5 to rotate. The flexspline 3 serves as a driven wheel, outputs rotation, and drives the chainring support 10 to move under load.

[0027] An assisted bicycle provided by the present application includes the structure of the hidden mid-drive motor described in the above preferred embodiment. The present application can not only have a long battery used by a common mid-drive motor, but also achieve the hidden effect that the motor is not exposed, providing a greater creative space for the frame designer in the innovative design of the electric bicycle shape.

[0028] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Structure of a hidden mid-mounted motor, characterized in that, It includes a housing, a motor for providing driving force, and a harmonic gear drivably connected to the output shaft of the motor. The harmonic gear includes a flexspline, a rigid spline, and a wave generator. The wave generator is inserted into the bottom bracket of the bicycle frame. The wave generator includes a cam and a flexible bearing. The inner ring of the flexible bearing is sleeved on the cam. The outer edge of the opening of the flexspline has teeth. The inner ring of the rigid spline has teeth. When the wave generator is inserted into the flexspline, the cross section of the flexspline becomes elliptical through elastic deformation, and the teeth of the flexspline and the teeth of the rigid spline engage and / or disengage.

2. The structure of a hidden mid-mounted motor according to claim 1, characterized in that, The teeth of the flexspline at both ends of the major axis of the wave generator engage with the teeth of the rigid spline. The teeth of the flexspline at both ends of the minor axis of the wave generator disengage from the teeth of the rigid spline. The teeth of the flexspline between the major axis and the minor axis of the wave generator are in a transitional state of engaging and disengaging with the teeth of the rigid spline.

3. The structure of a hidden mid-mounted motor according to claim 1, wherein, A rotor is sleeved on the bottom bracket. The rotor is connected to the output shaft of the motor. A stator is sleeved on the rotor. The rotor is electromagnetically connected to the stator. A first clutch is provided between the rotor and the wave generator.

4. The structure of a hidden mid-mounted motor according to claim 1, characterized in that, It further includes a chainring support. The driven end of the harmonic gear is connected to the chainring through the chainring support. A bearing assembly for supporting and positioning the chainring support is provided between the chainring support and the housing.

5. The structure of a hidden mid-mounted motor according to claim 4, characterized in that, The bottom bracket and the chainring support are connected through a second clutch.

6. The structure of a hidden mid-mounted motor according to claim 1, characterized in that, The flexspline is a thin-walled gear.

7. The structure of a hidden mid-mounted motor according to claim 1, characterized in that, The inner diameter of the flexspline is smaller than the major axis diameter of the wave generator.

8. The structure of a hidden mid-mounted motor according to claim 1, characterized in that, The wave generator adopts a mechanical wave generator with a rolling bearing.

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