Transmission device for electric bicycle

Abstract

A transmission device for an electric bicycle includes a driving motor, a first worm, a first transmission gear, a second worm, two first fan blade sets, a second transmission gear, a second fan blade set, and a crankshaft. The driving motor has a transmission shaft. The first worm is coaxially connected to the transmission shaft. The first transmission gear is meshed with the first worm. The second worm is coaxially connected to the first transmission gear, and the two first fan blade sets are disposed on the second worm. The two first fan blade sets are arranged along a first axial direction. The second transmission gear is meshed with the second worm. The second fan blade set is arranged on one side of the second transmission gear and along a second axial direction. The first axial direction is perpendicular to the second axial direction. The crankshaft is connected to the second transmission gear, and the second transmission gear is coaxially connected to the crankshaft.

Description

Technical Field

[0001] This invention relates to a transmission device, and more particularly to a transmission device for an electric bicycle. Prior Technology

[0002] Electric bicycles typically require high gear ratios in their transmission systems. To achieve this, the gear mechanism in the transmission system often employs a fixed-axis gear train design, meaning all gears are mounted on the same axis. Therefore, these gears are placed parallel to each other for transmission, a design that ensures relative stability during operation and prevents changes in their relative positions.

[0003] However, since all gears are mounted on the same axis, the space can be quite compact, limiting heat dissipation and making it difficult to effectively dissipate heat. Furthermore, even if airflow is generated inside the gear mechanism, the airflow direction is along a single axis; for example, the airflow only flows in a single direction along the gear axis. Therefore, this easily leads to poor heat dissipation efficiency within the transmission system.

[0004] Therefore, how to overcome the above-mentioned defects through structural design improvements has become one of the important problems to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a transmission device for an electric bicycle, which addresses the shortcomings of the prior art.

[0006] To solve the aforementioned technical problems, one technical solution adopted by the present invention is to provide a transmission device for an electric bicycle, comprising a drive motor, a first worm, a first transmission wheel, a second worm, two first blade sets, a second transmission wheel, a second blade set, and a crankshaft. The drive motor has a transmission shaft. The first worm is coaxially connected to the transmission shaft. The first transmission wheel meshes with the first worm. The second worm is coaxially connected to the first transmission wheel, and the second worm includes a worm body and a helical gear set on the worm body. Two first blade sets are disposed on the worm body and located on both sides of the helical gear set. The two first blade sets are arranged along a first axial direction. The second transmission wheel meshes with the second worm. The second blade set is disposed on one side of the second transmission wheel and arranged along a second axial direction. The first axial direction is perpendicular to the second axial direction. The crankshaft is connected to the second transmission wheel, and the second transmission wheel is coaxially connected to the crankshaft.

[0007] One of the beneficial effects of the present invention is that the transmission device of the electric bicycle provided by the present invention can improve the heat dissipation efficiency by means of the technical solutions of "two first blade groups arranged along the first axis", "the second blade group arranged along the second axis" and "the first axis perpendicular to the second axis".

[0008] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Simple Explanation of the Diagram

[0009] Figure 1 is a schematic diagram of the system architecture of the transmission device of an electric bicycle according to an embodiment of the present invention.

[0010] Figure 2 is a schematic diagram of the transmission device of an electric bicycle according to an embodiment of the present invention.

[0011] Figure 3 is a schematic diagram of the internal structure of the transmission device of an electric bicycle according to an embodiment of the present invention.

[0012] Figure 4 is a cross-sectional schematic diagram of the first worm gear and the second worm according to an embodiment of the present invention.

[0013] Figure 5 is a cross-sectional schematic diagram of the second worm gear and crankshaft according to an embodiment of the present invention. Implementation

[0014] The following specific embodiments illustrate the implementation of the "transmission device for an electric bicycle" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention. Furthermore, the accompanying drawings of this invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this invention in detail, but the disclosed content is not intended to limit the scope of protection of this invention. In addition, it should be understood that although terms such as "first," "second," and "third" may be used herein to describe various elements, these elements should not be limited by these terms. These terms are mainly used to distinguish one element from another. Furthermore, the term "or" used herein may, depending on the actual situation, include any combination of one or more of the associated listed items.

[0015] [Example]

[0016] Referring to Figures 1 to 3, Figure 1 is a schematic diagram of the system architecture of the transmission device of an electric bicycle according to an embodiment of the present invention, Figure 2 is a schematic diagram of the transmission device of an electric bicycle according to an embodiment of the present invention, and Figure 3 is an internal schematic diagram of the transmission device of an electric bicycle according to an embodiment of the present invention. An embodiment of the present invention provides a transmission device D for an electric bicycle, which includes a housing S, a drive motor 1, a first worm gear 2, a first transmission wheel 3, a second worm gear 4, two first blade groups 51, a second transmission wheel 6, a second blade group 52, and a crankshaft 7. The first worm gear 2, the first transmission wheel 3, the second worm gear 4, the two first blade groups 51, the second transmission wheel 6, the second blade group 52, and the crankshaft 7 are disposed within the housing S, while the drive motor 1 is disposed on one side of the housing S.

[0017] The drive motor 1 has a drive shaft 11. It should be noted that, for clarity, only the drive shaft 11 is shown in Figure 3, and the specific appearance of other parts of the drive motor 1 is not further shown. A first worm gear 2 is coaxially connected to the drive shaft 11, and the first worm gear 2 meshes with a first transmission wheel 3. A second worm gear 4 is coaxially connected to the first transmission wheel 3, and the second worm gear 4 meshes with a second transmission wheel 6. Furthermore, the crankshaft 7 is arranged along the X-axis, and the second transmission wheel 6 is directly mounted on the crankshaft 7 and coaxially connected to the crankshaft 7.

[0018] Referring again to Figure 3, the second worm 4 includes a worm body 41 and a helical gear 42 disposed on the worm body 41. The worm body 41 is arranged along the Z-axis. Two first blade sets 51 are disposed on the worm body 41 and located on both sides of the helical gear 42. The two first blade sets 51 are arranged along a first axial direction. The second blade set 52 is disposed on one side of the second transmission wheel 6 and is arranged along a second axial direction. The first axial direction is different from the second axial direction.

[0019] Specifically, as shown in Figure 3, since the second transmission wheel 6 is coaxially arranged with the crankshaft 7, the second axial direction of the second transmission wheel 6 and the second blade assembly 52 disposed on the second transmission wheel 6 is the same as the arrangement direction of the crankshaft 7, i.e., the X-axis direction. Furthermore, since the two first blade assemblies 51 are disposed on the worm gear body 41, the first axial direction of the two first blade assemblies 51 is the same as the arrangement direction of the worm gear body 41, i.e., the Z-axis direction. Therefore, more precisely, the arrangement direction (first axial direction) of the first blade assembly 51 is perpendicular to the arrangement direction (second axial direction) of the second blade assembly 52.

[0020] As shown in Figures 1 and 2, the crankshaft 7 has a first end 71 and a second end 72, both of which extend out of the housing S. A pedal E can be connected to each of the first and second ends 72 of the crankshaft 7. Furthermore, the drive motor 1 outputs power and transmits it to the crankshaft 7 via the drive shaft 11, the first worm gear 2, the first transmission wheel 3, the second worm gear 4, and the second transmission wheel 6, thereby driving the pedal E to rotate. Therefore, the drive motor 1 provides auxiliary power when the user rides the electric bicycle, thereby reducing the user's effort.

[0021] As can be seen from the above, when a user rides an electric bicycle, the second worm gear 4 and crankshaft 7 inside the transmission device D will continuously rotate (rotate), thereby driving the first blade assembly 51 disposed on the worm gear body 41 and the second blade assembly 52 disposed on the crankshaft 7 to rotate together, thus generating airflow in the first blade assembly 51 and the second blade assembly 52. ​​Since the configuration direction (first axis) of the first blade assembly 51 is perpendicular to the configuration direction (second axis) of the second blade assembly 52, the airflow direction generated by the first blade assembly 51 is perpendicular to the airflow direction generated by the second blade assembly 52.

[0022] Compared to the airflow generated by the gear mechanism of existing transmission systems, which flows in a single direction, the first blade group 51 and the second blade group 52 of this invention can generate two airflows that are perpendicular to each other and intersecting. The two airflows in different directions can cool and remove heat from different parts of the transmission device D respectively. Furthermore, the two perpendicular airflows can effectively agitate and disperse heat in different directions, creating an unstable turbulent state. This allows heat to be transferred more quickly from the component surface to the airflow, thereby increasing the efficiency of heat exchange.

[0023] Furthermore, the present invention is not limited to the form of the first transmission wheel 3 and the second transmission wheel 6. The first transmission wheel 3 can be a worm gear or a helical gear; similarly, the second transmission wheel 6 can be a worm gear or a helical gear. As shown in Figure 3, for example, in an embodiment of the present invention, the first transmission wheel 3 is a worm gear, and the second transmission wheel 6 is a helical gear. Additionally, in an embodiment of the present invention, the number of thread lines of the first worm 2 and the second worm 4 is greater than or equal to 2, that is, the first worm 2 and the second worm 4 are double-threaded or more. This design increases the lead angle of the worms (first worm 2 and second worm 4). Preferably, the lead angle of the first worm 2 and the second worm 4 can be designed to be greater than 4 degrees, that is, without self-locking function.

[0024] Referring to Figures 2, 4, and 5, Figure 4 is a cross-sectional schematic diagram of the first worm gear and the second worm according to an embodiment of the present invention, and Figure 5 is a cross-sectional schematic diagram of the second worm gear and the crankshaft according to an embodiment of the present invention. The transmission device D further includes a first one-way clutch 81 and a second one-way clutch 82. The first one-way clutch 81 is disposed within the first transmission wheel 3 and connected to the second worm 4, and the second one-way clutch 82 is disposed within the second transmission wheel 6 and connected to the crankshaft 7. A one-way clutch, also known as a one-way bearing, can only transmit power in a single direction (e.g., only clockwise or counterclockwise).

[0025] Additionally, as shown in Figure 1, the transmission device D also includes a torque sensor 9, which is mounted on the crankshaft 7 and electrically connected to the drive motor 1. The torque sensor 9 can detect the torque applied to the crankshaft 7.

[0026] Next, the operating sequence of the transmission device D of the present invention will be explained. When the user steps on the pedal E to drive the crankshaft 7, the torque sensor 9 detects the torque applied to the crankshaft 7 and outputs a signal to the drive motor 1 accordingly. The drive motor 1 outputs power according to a preset assist ratio (i.e., the ratio of the output power of the drive motor 1 to the force exerted by the user), which, together with the force exerted by the user stepping on the pedal E, propels the electric bicycle forward.

[0027] When the rotational speed of the pedal E is higher than the rotational speed of the drive motor 1, the first one-way clutch 81 can disengage the first transmission wheel 3 from the second worm gear 4, preventing the first transmission wheel 3 from driving the second worm gear 4 (i.e., power cannot be transmitted from the first transmission wheel 3 to the second worm gear 4). This prevents the user's pedal speed from being too fast and interfering with the operation of the drive motor 1.

[0028] On the other hand, when the user presses the pedal E in the opposite direction, causing the pedal E to rotate in the opposite direction, the second one-way clutch 82 can disengage the second drive wheel 6 from the crankshaft 7, preventing the second drive wheel 6 from driving the crankshaft 7 (i.e., power cannot be transmitted from the second drive wheel 6 to the crankshaft 7). In this way, interference with the operation of the drive motor 1 can be prevented by the user pressing the pedal E in the opposite direction.

[0029] [Beneficial Effects of the Examples]

[0030] The transmission device D of the electric bicycle provided by the present invention can improve heat dissipation efficiency by means of the technical solutions of "two first blade groups 51 arranged along the first axis", "second blade group 52 arranged along the second axis" and "the first axis is perpendicular to the second axis".

[0031] Furthermore, compared to the airflow generated by the gear mechanism of existing transmission systems, which flows in a single direction, the first blade group 51 and the second blade group 52 of this invention can generate two airflows that are perpendicular to each other and intersecting. These two airflows in different directions can cool and remove heat from different parts of the transmission device D. Moreover, the two perpendicular airflows can effectively agitate and disperse heat in different directions, creating an unstable turbulent state. This allows heat to be transferred more quickly from the component surface to the airflow, thereby increasing the efficiency of heat exchange.

[0032] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention specification and drawings are included in the scope of the patent application of the present invention.

[0033] D: Transmission device S: Shell 1: Drive motor 11: Drive shaft 2: First worm gear 3: First transmission wheel 4: Second worm gear 41: Worm Gear Body 42: Helical gear plate 51: First blade group 52: Second blade group 6: Second transmission wheel 7: Crankshaft 71: First End 72: Second end 81: First one-way clutch 82: Second one-way clutch 9: Torque sensor B: Ball bearings E: Foot pedal

Claims

1. A transmission device for an electric bicycle, comprising: A drive motor having a transmission shaft; A first worm gear is coaxially connected to the transmission shaft; A first transmission wheel meshes with a first worm; a second worm is coaxially connected to the first transmission wheel, the second worm including a worm body and a helical gear disposed on the worm body; two first fan-blade sets are disposed on the worm body and located on both sides of the helical gear, the two first fan-blade sets being arranged along a first axial direction; a second transmission wheel meshes with the second worm; a second fan-blade set is disposed on one side of the second transmission wheel and arranged along a second axial direction, the first axial direction being perpendicular to the second axial direction; and a crankshaft, the second transmission wheel being coaxially connected to the crankshaft.

2. The transmission device of the electric bicycle as described in claim 1, wherein, The airflow direction generated by the first two fan blade groups is perpendicular to the airflow direction generated by the second fan blade group.

3. The transmission device of the electric bicycle as described in claim 1, wherein, The first transmission wheel is a worm gear or a helical gear.

4. The transmission device of the electric bicycle as described in claim 1, wherein, The second transmission wheel is a worm gear or a helical gear.

5. The transmission device of the electric bicycle as described in claim 1, wherein, The number of thread lines in the first worm and the second worm is greater than or equal to 2.

6. The transmission mechanism of the electric bicycle as claimed in claim 1, wherein, The lead angle of the first worm and the second worm is greater than or equal to 4 degrees.

7. The transmission device of the electric bicycle as claimed in claim 1 further includes a first one-way clutch and a second one-way clutch, wherein the first one-way clutch is disposed in the first transmission wheel and the second one-way clutch is disposed in the second transmission wheel.

8. The transmission device of the electric bicycle as claimed in claim 1 further includes a torque sensor disposed on the crankshaft, the torque sensor being electrically connected to the drive motor.

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