Compact Bottom Bracket Torque Sleeve Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bottom bracket assemblies for pedal-operated vehicles, especially those with electric auxiliary drives, are compromised by increased width or length due to torque detection systems, negatively affecting pedal spacing (Q-factor) and ankle clearance.
Innovation Solution
A compact bottom bracket assembly design where the measuring sleeve extends between the first radial bearing and the bottom bracket shaft, allowing a non-rotatable connection and optimal torque transmission, maintaining a stable and dirt-resistant structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring sleeve is designed as a free-standing sleeve occupying almost the entire installation space between the two radial bearings, then reliable torque measurement is achieved, but the bottom bracket assembly becomes wider or longer, negatively affecting pedal spacing and ankle clearance
Solution Approach 1:
The measuring sleeve is nested within the bottom bracket assembly structure, specifically positioned between the first radial bearing and the bottom bracket axle. This nesting approach allows the measuring function to be integrated into the existing structural space rather than adding external components, thereby maintaining measurement reliability while minimizing the overall assembly length and preserving pedal spacing and ankle clearance
2Length of stationary object
If the measuring sleeve extends axially to a position between the first radial bearing and the bottom bracket axle, then a compact design is achieved, but the torque transmission path becomes more complex
Solution Approach 1:
The measuring sleeve acts as an intermediary element between the bottom bracket axle and the first radial bearing. It provides a rotationally fixed connection that enables torque transmission from the axle to the bearing while maintaining a compact axial arrangement. This intermediary role simplifies the overall torque path by creating a direct, controlled transmission route through the sleeve rather than requiring complex external torque sensing mechanisms
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 reliable and precise torque detection while maintaining a compact design, preserving pedal spacing and ankle clearance, suitable for bicycles with central electric motors.
Implementation Method 1
The torque can be detected by means of a stationary sensor, for example, via the twisting of the measuring sleeve or via the magnetoelastic effect
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a bottom bracket assembly for a pedal-powered vehicle, comprising a bottom bracket shaft defining an axis of the bottom bracket assembly and designed for connection to two pedals, a first radial bearing, and a second radial bearing axially extended therefrom for rotatably supporting the bottom bracket shaft, and a measuring sleeve arranged axially at least partially between the first radial bearing and the second radial bearing and enclosing the bottom bracket shaft for detecting a torque transmitted to the bottom bracket shaft via the pedals. A non-rotatable connection between the bottom bracket shaft and the measuring sleeve exists only at a first end of the two axial ends of the measuring sleeve.According to the invention, the measuring sleeve extends in the axial direction to a position between the first radial bearing and the bottom bracket shaft, so that at least a section of the measuring sleeve is arranged between the first radial bearing and the bottom bracket shaft.