Bicycle Bottom Bracket Shaft Encoder Ring Positioning
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Solution Overview
Problem
Existing bicycle bottom bracket shafts require costly and time-consuming post-processing to prevent axial slipping of encoder rings, leading to loss of measurement signals for speed, direction, and rotation, which increases production costs and complexity.
Innovation Solution
A shaft with two axially spaced radial bearings and a securing element formed from at least two parts, where the measuring value transmitter is secured against axial displacement, allowing for precise transmission of dynamic parameters without extensive reworking, using a polymer plastic securing element that eliminates the need for costly post-processing and ensures non-slip functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bottom bracket shaft is extensively reworked with regrinding and surface smoothing to achieve press fit with encoder ring, then axial slipping is prevented and measurement signal is maintained, but production time increases and manufacturing costs rise
Solution Approach 1:
The patent applies preliminary action by providing the shaft with axially extending positioning protrusions and annular grooves during the initial manufacturing process, before encoder ring installation. These features are pre-formed on the shaft surface, enabling the encoder ring to be directly pressed onto the shaft without requiring subsequent regrinding or surface smoothing operations. This preliminary preparation eliminates the need for time-consuming post-processing while ensuring reliable axial positioning and preventing encoder ring slippage.
2Reliability
If the bottom bracket shaft is extensively reworked to achieve press fit with encoder ring, then axial slipping is prevented, but additional production costs are incurred
Solution Approach 1:
The positioning protrusions and annular grooves are incorporated into the shaft manufacturing process itself, allowing standard production methods to create the necessary features. This eliminates the need for costly post-processing operations like regrinding and surface smoothing, thereby reducing manufacturing costs while maintaining reliable encoder ring positioning and preventing axial slipping.
3Strength
If a solid material shaft is used with two roller bearings, then structural support is provided, but the shaft cannot accommodate measuring transducers without extensive post-processing
Solution Approach 1:
The patent applies local quality by modifying specific localized regions of the shaft surface to create positioning protrusions and annular grooves, while maintaining the overall solid material construction and structural integrity of the shaft. These localized modifications are made during standard manufacturing processes, allowing the shaft to simultaneously provide robust structural support for the roller bearings and accommodate measuring transducers like the encoder ring without requiring extensive post-processing of the entire shaft.
Data Source
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AI summary
Disclosed is a shaft (1) for a bicycle bottom bracket (2) having two axially spaced-apart radial bearings (3, 4) for supporting the shaft (1). This shaft is characterized by a multi-part securing element (7) arranged axially between the radial bearings (3, 4) on the shaft (1), and at least one transducer (9) arranged on this securing element (7), wherein the securing element (7) is secured against axial displacement (A10) by at least one form-fit with the shaft (1), and wherein the securing element (7) comprises two parts (7a, 7b) and is coupled to the shaft (1) such that the at least one transducer (9) is fixed in the axial direction by resting flat against the two parts (7a, 7b).