Bicycle hub planetary speed change device

Abstract

The invention discloses a bicycle hub planetary speed change device, and belongs to the technical field of bicycle parts. The device mainly comprises a fixed sun gear, a power input tower footing assembly, a power output hub and at least one stage of planetary gear speed increasing mechanism integrated in the hub. The sun gear is fixed to the frame through a shaft sleeve and an end cover, and the tower footing assembly transmits power to the planet carrier through a ratchet mechanism. The planet gear on the planet gear carrier is meshed with the sun gear and the outer gear ring to drive the outer gear ring and the hub to rotate at a higher rotating speed, so that the power output rotating speed is obviously higher than the input rotating speed under the same power input rotating speed, and the driving mode of 1: 1 synchronous meshing of a traditional hub is effectively changed. By arranging a single-stage or multi-stage series planetary gear mechanism, different speed increasing ratios can be achieved. The speed increasing mechanism is compact in structure, the speed increasing mechanism is internally packaged, transmission is stable and reliable, and the riding speed is effectively increased.

Description

Technical Field

[0001] This invention relates to the field of bicycle component technology, specifically to a bicycle hub planetary gear shifting device. Background Technology

[0002] This invention relates to the field of bicycle component technology, and more specifically to a planetary gear shifting device built into a bicycle hub.

[0003] As a green and environmentally friendly means of transportation and a popular fitness tool, the transmission efficiency and gear shifting performance of bicycles have always been the core of technological development. Currently, common bicycle gear shifting systems are mainly divided into two categories: external derailleurs and internal derailleurs.

[0004] External derailleur systems achieve gear shifting by switching the chain between sprockets and freewheels of different sizes. This system is technologically mature and has a wide gear range, but its transmission components (such as derailleurs and exposed chains) are completely exposed, making them susceptible to contamination from mud, rain, and impact damage. They require frequent maintenance and have lower reliability under complex road conditions.

[0005] For users seeking a high-speed riding experience (such as on flat roads or downhill sections), existing bicycles typically rely on a combination of a large chainring and a small cassette to achieve a high gear ratio. However, this approach is limited by the maximum size of the chainring and the minimum size of the cassette, resulting in limited speed increase and often causing the chain to tilt, accelerating wear. Simultaneously, riders need extremely high cadence to maintain high speeds, leading to fatigue. While some simple speed-increasing hub designs exist, their speed ratios are limited, their structures are not compact enough, or they struggle to achieve substantial and scalable speed increases within a limited space.

[0006] Therefore, there is an urgent need in the field for a bicycle hub gearshift device that is relatively simple and compact in structure, can provide a significant and adjustable speed ratio, and also has the advantages of sealed and reliable internal gearshift systems. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a bicycle hub gearshift device that is relatively simple and compact in structure and can provide a significant speed increase ratio.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a bicycle hub planetary gear shifting device, comprising: The sun gear is configured to be fixed and non-rotatable; A power input unit, configured to receive input power from the chain; A power take-off unit configured to drive the rear wheel of a bicycle; A planetary gear speed-increasing mechanism is connected between the power input unit and the power output unit; The rotational motion of the power input unit is transmitted to the power output unit through the planetary gear speed-increasing mechanism, and the rotational speed of the power output unit is higher than that of the power input unit.

[0009] Furthermore, the planetary gear speed-increasing mechanism includes: A primary planetary gear carrier, which is connected to the power input unit via a transmission; At least one planetary gear is rotatably mounted on the first-stage planetary gear carrier; And the first-stage external gear ring; The planetary gear meshes with both the sun gear and the primary external gear ring, and the primary external gear ring is connected to the power output unit via a transmission connection.

[0010] Furthermore, the planetary gear speed-increasing mechanism is multi-stage, and the multi-stage planetary gear speed-increasing mechanisms are connected in series, with the output of the previous stage planetary gear speed-increasing mechanism driving the input of the next stage planetary gear speed-increasing mechanism.

[0011] Furthermore, the multi-stage planetary gear speed-increasing mechanism also includes: The second-stage planetary gear carrier is driven by the first-stage planetary gear carrier; At least one planetary gear is rotatably mounted on the secondary planetary gear carrier; And the secondary external gear ring; The planetary gears on the secondary planetary gear carrier mesh with both the sun gear and the secondary external gear ring, and the secondary external gear ring is fixedly connected to the power output unit.

[0012] Furthermore, the power input unit is a tower base assembly, which is connected to the planetary gear speed-increasing mechanism through a one-way transmission mechanism.

[0013] Furthermore, it also includes a bushing; the sun gear is fixedly connected to the bushing; both ends of the bushing are configured to be fixed to the bicycle frame via end caps.

[0014] Furthermore, the power output unit is a hub, which is supported on the bushing by a bearing.

[0015] Furthermore, the outer contour of the end cap that contacts the bicycle frame is non-circular to prevent slippage when engaging with the rear fork of the frame.

[0016] Furthermore, the outer surfaces of both ends of the bushing are provided with snap-fit ​​protrusions, and the inner wall of the end cap is provided with snap-fit ​​grooves corresponding to the snap-fit ​​protrusions, so as to prevent relative rotation through the interlocking of the protrusions and the concave-convex joint.

[0017] Furthermore, the sun gear and the bushing are either integrally formed or separate structures.

[0018] The beneficial effects of this invention are as follows: 1. Achieves highly efficient built-in speed increase: This invention creatively integrates a planetary gear speed increase mechanism inside the bicycle hub. Through a transmission mode of "fixed sun gear, planetary carrier input, and ring gear output," the speed of the hub (output end) is higher than that of the freehub (input end). This provides riders with higher cadence utilization in scenarios such as flat roads and downhill slopes, effectively improving riding speed and solving the problem of excessively high cadence and decreased efficiency when riding at high speeds in traditional fixed-ratio bicycles.

[0019] 2. Compact structure and high space utilization: Planetary gear transmission features power splitting and coaxial transmission, with all gears arranged around the same central axis. This allows the entire gearing system to be perfectly accommodated within the limited space of a standard hub, without requiring changes to the existing frame rear fork opening size. It is highly versatile and easy to modify or apply to existing bicycles.

[0020] 3. Precise gear ratio and strong scalability: The gear ratio of the device is determined by the number of teeth on the sun gear and the external gear ring, resulting in a stable and precise transmission ratio. This invention can adopt a modular design with single-stage or multi-stage series connection. By simply increasing the number of stages in the planetary gear speed-increasing mechanism, the overall transmission ratio (product of the transmission ratios of each stage) can be significantly increased with almost no increase in radial dimension, thus flexibly meeting different needs from light to heavy speed-increasing and providing excellent scalability.

[0021] 4. Smooth transmission and high reliability: In planetary transmissions, multiple planetary gears share the load, resulting in smoother gear meshing, less impact and vibration, high load-bearing capacity, and low operating noise. Simultaneously, the core transmission components are sealed inside the hub, receiving excellent lubrication and protection, leading to a long service life and high reliability. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a bicycle hub gear shifter with a single-stage planetary gear transmission.

[0023] Figure 2 This is a cross-sectional schematic diagram of a bicycle hub gearbox with a single-stage planetary gear transmission.

[0024] Figure 3 This is a schematic diagram of the exploded structure of the tower base component.

[0025] Figure 4 This is an explosive schematic diagram of the assembly of the first-stage planetary gear carrier.

[0026] Figure 5 This is a schematic diagram of the bushing structure.

[0027] Figure 6 This is a schematic diagram of the end cap structure.

[0028] Figure 7 This is a cross-sectional schematic diagram of a bicycle hub gearbox with a two-stage planetary gear transmission.

[0029] Figure 8 This is a schematic diagram of the explosion of the second-stage planetary gear carrier assembly.

[0030] Figure 9 This is an exploded structural diagram of a bicycle hub gearbox with a two-stage planetary gear transmission.

[0031] Explanation of reference numerals: 1. Sun gear; 2. First-stage planetary gear carrier; 2a. Planetary gear cover; 2b. Ratchet seat; 2c. First-stage planetary gear shaft; 2d. First-stage planetary bearing; 2e. First-stage planetary gear; 2f. Screw; 3. Second-stage planetary gear carrier; 3a. First and second-stage planetary gear covers; 3b. Second and second-stage planetary gear covers; 3c. Second-stage planetary gear shaft; 3d. Second-stage planetary bearing; 3e. Second-stage planetary gear; 4. Tower base assembly; 41. Tower base shell; 42. Drive ratchet; 43. Preload spring; 44. Freeloader base support sleeve; 45. External support sleeve; 5. Secondary external gear ring; 6. Hub; 7. Bushing; 71. Snap-fit ​​protrusion; 8. Bearing; 10. Freeloader base end cap; 11. End cap; 111. Snap-fit ​​groove; 12. Primary external gear ring. Detailed Implementation

[0032] Please see Figure 1-6 As shown, Example 1 This embodiment demonstrates a bicycle hub shifter employing a single-stage planetary gear transmission. The core of this device lies in using a planetary gear mechanism to amplify the input power from the freehub base before transmitting it to the hub, thereby driving the rear wheel.

[0033] The specific structure of the device includes a sun gear 1, which is fixedly connected to a bushing 7 via a spline in its inner hole. The bushing 7 can be made of aluminum alloy, steel, or high-strength engineering plastic, and is not limited to a specific material. The left and right ends of the bushing 7 are fixed to the rear fork of the bicycle frame by a drive-side end cap 11 and a freehub end cap 10, respectively. To ensure reliable fixation and prevent slippage under force, the outer contours of the freehub end caps 10 and 11 that mate with the frame are designed to be non-circular, such as regular hexagonal or irregularly shaped with anti-slip teeth. Simultaneously, raised engaging protrusions 71 are provided on the outer surfaces of both ends of the bushing 7, while engaging grooves 111 that precisely match these engaging protrusions 71 are machined on the inner walls of the freehub end caps 10 and 11. This interlocking method further eliminates the possibility of relative rotation between the bushing 7 and the freehub end caps 10 and 11. With the above structure, the sun gear 1 is securely locked and remains stationary throughout the entire operation.

[0034] The specific components of the supercharger base assembly 4 include a basic supercharger housing 41 for mounting the flywheel; a drive ratchet 42, which is connected to the supercharger housing 41 via an internal spline or keyway and can move slightly axially; a preload spring 43, which provides axial preload to the drive ratchet 42, causing it to tend to engage with the ratchet on the ratchet seat 2b; and a supercharger support sleeve 44 for supporting and positioning internal parts. Furthermore, the supercharger base assembly 4 is supported on the bushing 7 by two independent bearings 8 to ensure smooth rotation. To ensure the axial positioning accuracy of the supercharger base assembly 4 and the internal transmission system, an external support sleeve 45 is also included. This external support sleeve 45 is fitted onto the bushing 7, with one end pressed against the inner ring end face of the bearing 8 supporting the supercharger base assembly 4, and the other end pressed against the end face of the sun gear 1. Through the precise positioning of this external support sleeve 45, the supercharger base assembly 4 can rotate normally and smoothly relative to the bushing 7, preventing axial movement of the entire transmission system.

[0035] When the rider pedals, the chain drives the freehub housing 41 and the drive ratchet 42 to rotate. Under the pressure of the preload spring 43, the drive ratchet 42 engages with the ratchet on the ratchet seat 2b, thereby transmitting power to the first-stage planetary gear carrier 2. When pedaling stops or when reverse force is applied, the drive ratchet 42 overcomes the spring pressure and disengages from the ratchet on the ratchet seat 2b, achieving unidirectional transmission and gliding function. This structure is a conventional design in the art, and its specific details are not the focus of this invention, but are described here to make the solution more complete.

[0036] The specific structure and assembly of the primary planetary gear carrier 2 are as follows: The primary planetary gear carrier 2 is firmly assembled together by a planetary gear cover 2a and a ratchet seat 2b using multiple circumferentially distributed screws 2f, forming a frame structure that can accommodate planetary gears. Multiple primary planetary gear shafts 2c are fixedly mounted on the assembled primary planetary gear carrier 2. On each primary planetary gear shaft 2c, a primary planetary bearing 2d (such as a miniature needle roller bearing or ball bearing) is first fitted, and then a primary planetary gear 2e is fitted onto the outer ring of the primary planetary bearing 2d. In this way, each primary planetary gear 2e can rotate smoothly on the planetary gear shaft 2c via the primary planetary bearing 2d. When the rider pedals, driving the freehub assembly 4 to rotate clockwise, its internal drive ratchet 42 engages with the ratchet on the ratchet seat 2b, thereby transmitting power to the entire primary planetary gear carrier 2. After being driven, the primary planetary gear carrier 2 causes all the primary planetary gears 2e on it to revolve around the fixed sun gear 1. Due to the meshing relationship between the first-stage planetary gear 2e and the fixed sun gear 1, the first-stage planetary gear 2e will rotate. The rotation and revolution of the first-stage planetary gear 2e together drive the first-stage external gear ring 12, which meshes with it, to rotate at a higher speed. The first-stage external gear ring 12 is fixedly connected to the hub 6 by threads on its outer wall. The hub 6 is supported on the bushing 7 by the bearing 8, thereby outputting power to the rear wheel.

[0037] In this embodiment, the primary external gear ring 12 is directly screwed and fixed to the inner wall of the hub 6 assembly via threads on its outer wall. Of course, the connection method between the external gear ring and the hub 6 is not limited to threaded connection; it can also be interference fit, fixed with circumferential bolts, or connected by a spline, as long as torque can be reliably transmitted. The hub 6 itself is also supported on the bushing 7 via bearing 8 and is used to drive the bicycle rear wheel.

[0038] Taking a specific gear parameter as an example: if a single-stage transmission is used, and the sun gear 1 is fixed, with the planetary gear teeth numbering 12, the sun gear 1 teeth numbering 24, and the outer ring gear teeth numbering 48, then the equivalent number of teeth on the planetary carrier = sun gear 1 teeth + outer ring gear teeth = 24 + 48 = 72, and the transmission ratio = 72 / 48 = 1.5. This means that the output speed of hub 6 and the rear wheel is 1.5 times the input speed of freehub assembly 4, achieving a speed increase effect, suitable for high-speed riding on flat roads. When the rider stops pedaling, the active ratchet 42 in freehub assembly 4 slips, allowing the rear wheel to slide freely.

[0039] Example 2

[0040] Please see Figure 1-9 As shown, in this embodiment, based on the single-stage transmission structure of embodiment one, a planetary gear speed-increasing mechanism is added to form a two-stage series speed-increasing system, so as to achieve a larger transmission ratio and meet the riding scenarios with higher speed requirements.

[0041] This embodiment includes the fixed part (sun gear 1 is fixed to the frame via bushing 7 and end caps 10 and 11 with anti-rotation structure) from Embodiment 1, the power input part (freeloader assembly 4 and drive ratchet 42), and the hub 6, among other basic components. Its core improvement lies in the power transmission path and the specific mechanical structure of the secondary transmission part.

[0042] The specific structure of the secondary planetary gear carrier assembly is as follows: The secondary planetary gear carrier 3 adopts a modular split design, mainly composed of a first secondary planetary gear cover 3a and a second secondary planetary gear cover 3b. These two covers are firmly assembled together by circumferentially distributed screws to form a complete frame. In particular, the primary external gear ring 12 is directly fixed to the side of the first secondary planetary gear cover 3a by bolts, making the two a synchronously rotating whole. Multiple secondary planetary gear shafts 3c are fixedly installed on the assembled secondary planetary gear carrier 3. On each secondary planetary gear shaft 3c, a secondary planetary bearing 3d is first fitted, and then the secondary planetary gear 3e is fitted onto the outer ring of the secondary planetary bearing 3d, so that each secondary planetary gear 3e can rotate smoothly around its own axis.

[0043] Detailed description of the power transmission path: Power is input from the base assembly 4 and drives the first-stage planetary gear carrier 2 to rotate via the active ratchet 42. When the first-stage planetary gear carrier 2 rotates, the planetary gears 12 on it drive the first-stage external gear ring 12 to rotate. Since the first-stage external gear ring 12 is fixedly mounted on the second-stage planetary gear carrier 3, the rotation of the first-stage external gear ring 12 directly drives the entire second-stage planetary gear carrier 3 to rotate at the same speed, thus using the output of the first-stage transmission as the input of the second-stage transmission.

[0044] At this point, the secondary planetary gear carrier 3, serving as the input end of the second-stage transmission, drives all the secondary planetary gears 3e on it to revolve around the fixed sun gear 1. Simultaneously, due to the meshing relationship between the secondary planetary gears 3e and the fixed sun gear 1, they will rotate on their own axes. The rotation and revolution of the secondary planetary gears 3e together drive the secondary external gear ring 5, which meshes with them, to rotate at a higher speed. The secondary external gear ring 5 is ultimately fixed to the hub 6 via a threaded connection or other means, outputting the power, which has undergone two speed increases, to the rear wheel.

[0045] Regarding gear parameters, for ease of manufacturing, the same tooth configuration as in Embodiment 1 can be used, i.e., the sun gear 1 has 24 teeth, each planetary gear has 12 teeth, and the secondary external gear ring 5 also has 48 teeth. Therefore, the transmission ratio i1 of the first stage is 1.5, and the transmission ratio i2 of the second stage is also 1.5. The total transmission ratio i_total after the two stages are connected in series is the product of the transmission ratios of each stage, i.e., i_total = i1 × i2 = 1.5 × 1.5 = 2.25. This means that the final speed of the hub 6 is 2.25 times the input speed of the freehub assembly 4, and the speed increase effect is more significant than that of a single-stage transmission. This modular design allows for flexible acquisition of different gear ratios within a limited space by increasing the number of transmission stages, demonstrating the scalability advantage of this invention. The coasting function is also implemented by the active ratchet 42.

[0046] In summary, this invention achieves built-in speed increase in bicycle hubs through a clever planetary gear mechanism layout, resulting in a compact structure, a clearly defined gear ratio, and strong scalability. Those skilled in the art should understand that, without departing from the principles of this invention, various improvements and modifications can be made to the gear parameters, connection methods, and specific structural details in the above embodiments, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A bicycle hub planetary gear device, characterized by, include: The sun gear is configured to be fixed and non-rotatable; A power input unit, configured to receive input power from the chain; A power take-off unit configured to drive the rear wheel of a bicycle; A planetary gear speed-increasing mechanism is connected between the power input unit and the power output unit; The rotational motion of the power input unit is transmitted to the power output unit through the planetary gear speed-increasing mechanism, and the rotational speed of the power output unit is higher than that of the power input unit.

2. The bicycle hub planetary derailleur device according to claim 1, wherein, The planetary gear speed-increasing mechanism includes: A primary planetary gear carrier, which is connected to the power input unit via a transmission; At least one planetary gear is rotatably mounted on the first-stage planetary gear carrier; And the first-stage external gear ring; The planetary gear meshes with both the sun gear and the primary external gear ring, and the primary external gear ring is connected to the power output unit via a transmission connection.

3. The bicycle hub planetary derailleur of claim 2 wherein, The planetary gear speed-increasing mechanism is multi-stage, and the multi-stage planetary gear speed-increasing mechanisms are connected in series. The output of the previous stage planetary gear speed-increasing mechanism drives the input of the next stage planetary gear speed-increasing mechanism.

4. The bicycle hub planetary derailleur of claim 3 wherein, The multi-stage planetary gear speed-increasing mechanism further includes: a secondary planetary gear carrier driven by the primary planetary gear carrier; at least one planetary gear rotatably mounted on the secondary planetary gear carrier; and a secondary external gear ring; wherein the planetary gears on the secondary planetary gear carrier simultaneously mesh with the sun gear and the secondary external gear ring, and the secondary external gear ring is fixedly connected to the power output unit.

5. The bicycle hub planetary derailleur of claim 1 wherein, The power input unit is a tower base assembly, which is connected to the planetary gear speed-increasing mechanism through a one-way transmission mechanism.

6. The bicycle hub planetary derailleur of claim 1 wherein, It also includes a bushing; the sun gear is fixedly connected to the bushing; both ends of the bushing are configured to be fixed to the bicycle frame via end caps.

7. A bicycle hub planetary gear device according to claim 6, characterised in that, The power output unit is a hub, which is supported on the bushing by a bearing.

8. The planetary bicycle hub derailleur of claim 6 wherein, The outer contour of the end cap that contacts the bicycle frame is non-circular to prevent slippage when it is engaged with the rear fork of the frame.

9. The planetary bicycle hub derailleur of claim 6 wherein, The outer surfaces of both ends of the bushing are provided with snap-fit ​​protrusions, and the inner wall of the end cap is provided with snap-fit ​​grooves corresponding to the snap-fit ​​protrusions, so as to prevent relative rotation through the interlocking of the protrusions and the concave-convex fit.

10. The planetary bicycle hub derailleur of claim 6 wherein, The sun gear and the bushing are either integrally formed or separate structures.

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