Freehub Torque Sensing With Wireless Power and Signal Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing torque sensors for electric bicycles are often bulky, inconvenient to assemble, and prone to damage due to their external placement, which complicates the integration of bilateral torque and speed sensing.
Innovation Solution
A freehub torque and speed sensing device is integrated into the freehub of an electric bicycle, featuring a torque sensing deformation unit with sensors that detect deformation and generate torque signals, along with a dynamic and static assembly for wireless signal transmission and power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque sensor is disposed on outer side of motor, then torque sensing function is achieved, but assembly convenience deteriorates and sensor reliability deteriorates
Solution Approach 1:
The patent integrates the torque sensor directly into the freehub body, merging the sensor function with the existing structural component. This eliminates the need for separate external sensor mounting, thereby improving both assembly convenience and sensor protection while maintaining reliable torque sensing capability through the deformation unit embedded in the freehub structure
Solution Approach 2:
The sensor is nested within the freehub body structure, with the deformation unit integrated into the freehub's internal geometry. This nesting approach protects the sensor from external damage while keeping it functionally accessible, resolving the contradiction between protection and operational accessibility
2Reliability
If separate sensor circuit is required, then torque sensing function is achieved, but device complexity increases
Solution Approach 1:
The patent combines the sensor, deformation unit, and signal processing into a single integrated freehub assembly. The torque sensing function is achieved through the deformation unit's direct mechanical coupling with the load connection portion, eliminating separate sensor circuits and reducing overall device complexity
Solution Approach 2:
The freehub body serves multiple functions: it provides the structural framework for the drivetrain, houses the torque sensor, and contains the deformation unit. This multi-functionality reduces the need for separate dedicated components, thereby simplifying the overall device complexity while maintaining reliable torque sensing
3Reliability
If sensor is exposed outside motor, then torque sensing is achieved, but sensor durability deteriorates
Solution Approach 1:
The sensor and deformation unit are nested within the protected interior of the freehub body, shielded from external environmental factors and mechanical damage. This nesting maintains full torque sensing capability while significantly reducing exposure to harmful factors such as water, dust, and physical impact
Solution Approach 2:
The freehub body structure itself serves as a protective cushioning layer around the sensor and deformation unit. This structural protection is built-in from the design stage, preventing direct exposure to harmful external factors while maintaining the sensor's functional integrity
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
This solution enables convenient and safe assembly of the electric bicycle, achieves bilateral torque and speed sensing, and ensures a reasonable structure with long service life, simple production, and high signal stability through wireless power and signal transmission.
Implementation Method 1
A torque sensing deformation unit is disposed at a journal of the freehub body adjacent to the load connection portion and includes at least one sensor, where the at least one sensor is configured to sense a deformation magnitude of the torque sensing deformation unit and form a torque signal
Implementation Method 2
The primary induction coil and the secondary induction coil are configured to perform signal transmission between the primary induction coil and the secondary induction coil in the wireless manner, and the primary signal processor is configured to supply power to the secondary signal processor through the primary induction coil and the secondary induction coil
Implementation Method 3
the primary signal processor and the secondary signal processor are configured to perform wireless signal transmission between the primary signal processor and the secondary signal processor through an infrared component
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Provided is a freehub torque and speed sensing device, including a freehub, a dynamic assembly and a static assembly. The freehub includes a freehub body (2) and a freehub fixing housing (1) sleeved on an outer side of the freehub body (2). A load connection portion (204) is disposed at one end of the freehub body (2). A torque sensing deformation unit (203) is disposed at the freehub body (2) adjacent to the load connection portion (204) and includes at least one sensor. The dynamic assembly rotates with the freehub body (2). The static assembly is fixedly connected to an external fixing structure body and includes a primary control unit. The dynamic assembly includes a secondary control unit electrically connected to the sensor. A torque signal is transmitted between the primary control unit and the secondary control unit in a wireless manner, and the primary control unit supplies power to the secondary control unit in the wireless manner. In this manner, the whole vehicle assembly is more convenient and safer, and the signal stability is high.