Internally Geared Hub with Bidirectional Planetary Gearing for Regenerative Charging
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Solution Overview
Problem
Conventional internally geared hubs for bicycles do not allow regenerative charging of the battery in electric motor-assisted bicycles, as they lack a mechanism to transmit rotation from the hub shell back to the driver during coasting.
Innovation Solution
An internally geared hub with a planetary gear mechanism that includes both driver rotation transmission paths and hub shell rotation transmission paths, enabling rotation of the hub shell to be transmitted back to the driver during coasting, allowing for regenerative charging by driving the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional internally geared hub with one-way clutch is used, then the service life of the hub is extended and coasting is enabled, but regenerative charging cannot be performed because rotation of the hub shell cannot be transmitted back to the driver
Solution Approach 1:
The patent applies dynamics by making the transmission path configurable rather than fixed. The hub can dynamically switch between one-way clutch engagement (for coasting and reliability) and two-way rotation transmission (for regenerative charging). This is achieved through a controller that activates the electric motor as a generator during regenerative charging modes, enabling bidirectional rotation transmission while maintaining the structural integrity and reliability benefits of the conventional design
Solution Approach 2:
The patent implements multi-functionality by enabling the hub to perform multiple functions: traditional gear transmission, coasting with one-way clutch, and regenerative charging. The electric motor serves dual purposes as both a drive motor and a generator for regenerative charging. The rotation transmission mechanism universally handles both forward (driver to hub shell) and reverse (hub shell to driver) rotation directions, making the hub adaptable to various operating modes including acceleration, coasting, and energy recovery
2Ease of operation
If a one-way clutch is used to enable coasting, then the hub shell rotation is decoupled from the driver during coasting, but this prevents torque transmission to pedals and regenerative charging
Solution Approach 1:
The system dynamically transitions between one-way clutch engagement (during normal coasting) and two-way rotation transmission (during regenerative charging). The controller monitors operating conditions and activates the electric motor as a generator when regenerative charging is desired, temporarily overriding the one-way clutch behavior to allow reverse rotation transmission from hub shell to driver, enabling energy recovery while maintaining easy coasting operation under normal conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables regenerative charging by allowing the electric motor to utilize the rotation of the hub shell to charge the battery, improving the service life of the hub and enhancing the efficiency of the bicycle's energy recovery system.
Implementation Method 1
The planetary gear mechanism of the rotation transmitting mechanism transmits rotation of the driver to the hub shell through one of a plurality of gears (gear ratios)
Implementation Method 2
the conventional internally geared hub is provided with a one-way clutch serving to transmit rotation of a carrier of the planetary gear mechanism to the hub shell only in a drive direction
Data Source
AI summary
An internally geared hub is provided with a hub axle (12), a hub shell (14), a driver (16), a planetary gear mechanism (32) and a gear changing mechanism (20). The hub shell (14) rotates freely about the hub axle (12). The driver (16) rotates freely relative to both the hub axle (12) and the hub shell (14). The planetary gear mechanism (32) is operatively connected between the hub shell (14) and the driver (16). The planetary gear mechanism (32) includes a plurality of driver rotation transmission paths that transmits rotation of the driver in a prescribed operating direction to the hub shell, and a hub shell rotation transmission path that transmits rotation of the hub shell in the prescribed operating direction to the driver. The gear changing mechanism (20) is operatively connected to the planetary gear mechanism (32) for selectively establishing one of the driver rotation transmission paths or the hub shell rotation transmission path.