Bicycle Bottom Bracket with Identical Roller Bearings
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Solution Overview
Problem
Existing bottom bracket systems face issues with durability and ease of assembly, particularly in the smaller-sized roller bearing assigned to the chainring carrier, which is more heavily loaded but less load-bearing due to its dimensional design, and lack the ability to detect torques applied on both sides of the pedals effectively.
Innovation Solution
A bottom bracket design featuring two roller bearings with identical dimensions and load-bearing capacities, integrated sensors for torque and rotation measurement, and a measuring sleeve and output sleeve in one piece, allowing for improved torque transmission and assembly, with sensors housed within the bicycle frame for enhanced durability and power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the smaller-sized roller bearing is used for the chainring carrier, then the device complexity is reduced, but the reliability deteriorates due to unequal load-bearing capacity
Solution Approach 1:
The patent applies local quality by making both roller bearings identical in size and load-bearing capacity, regardless of the different torque loads they experience. This ensures that both bearings have equal durability and reliability, resolving the issue where the smaller bearing would fail prematurely under heavy chainring carrier loads.
2Measurement precision
If torque measurement is implemented, then the measurement precision is improved, but the device complexity increases due to additional sensors and evaluation units
Solution Approach 1:
The patent replaces mechanical torque measurement mechanisms with magnetic field-based sensors that detect torque through magneto-elastic effects in the measuring sleeve. This substitution provides precise torque measurement without complex mechanical linkages or electrical contacts, reducing overall system complexity while maintaining high measurement accuracy.
3Manufacturing precision
If the measuring sleeve and output sleeve are integrated into one piece, then the manufacturing precision is improved, but the adaptability deteriorates due to reduced flexibility in assembly variations
Solution Approach 1:
The patent merges the measuring sleeve and output sleeve into a single integrated component. This eliminates potential misalignment issues between separate parts and ensures precise torque transmission from the pedals through the measurement system to the chainring carrier, while the modular design of the entire bottom bracket system maintains assembly flexibility.
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
The design enhances the durability and strength of the bottom bracket by using larger, equally dimensioned roller bearings and integrates sensors within the bicycle frame, enabling effective torque detection on both sides and improved assembly, thus addressing the limitations of existing systems.
Implementation Method 1
an incremental encoder arranged on the front side of the measuring sleeve, on the side facing away from the output sleeve, which is provided for measuring the speed and direction of rotation of the drive shaft
Implementation Method 2
The torque load within the drive shaft 2 and the measuring sleeve 8, which hardly leads to a torsion of the measuring sleeve 8, can be detected via changed magnetic properties of the measuring sleeve 8. This so-called magneto-elastic effect used for torque measurement
Data Source
Figure 1~2
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Figure 4
AI summary
The invention relates to a bottom bracket (1) with a drive shaft (2) which is provided for connection with two pedals, two rolling bearings (5, 6) supporting the drive shaft (2), wherein the rolling bearings (5, 6) are each arranged in a housing part (3, 4) comprising a thread (3a, 4a), a measuring sleeve (8) arranged axially between the rolling bearings (5, 6) and enclosing the drive shaft (2), an output sleeve (10) arranged in axial extension of the measuring sleeve (8) and non-rotatably connected to it, and provided for connection with a chainring carrier (11), wherein the measuring sleeve (8) and the output sleeve (10) are formed in one piece, an incremental encoder (17) arranged on the end face of the measuring sleeve (8), on the side facing away from the output sleeve (10), which is provided for measuring the speed and direction of rotation of the drive shaft (2), and a coaxially surrounding the measuring sleeve (8). Evaluation unit (14),which interacts with the measuring sleeve (8) and with the incremental encoder (17), wherein the two rolling bearings (5, 6) have, according to the invention, identically dimensioned outer rings (5a, 6a) and rolling elements (5b, 6b). The invention further relates to a bicycle with such a bottom bracket (1).