Bicycle Gear Actuator with Deflectable Element
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Solution Overview
Problem
Conventional gear shift mechanisms for bicycles require high precision in the interaction between actuating and displacement elements, which is difficult to maintain due to thermal changes and external impacts, leading to potential malfunctions and wear from rubbing contacts during shifting.
Innovation Solution
An adjustable actuating element that can be held in a deflectable manner, allowing it to automatically align with displacement elements during rotation, reducing the need for exact positioning and minimizing rubbing contacts through a rolling interaction, with a restoring element ensuring precise guidance and automatic return to prevent collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high precision positioning of actuating element is used to ensure accurate engagement with displacement elements, then shifting reliability is improved, but the system becomes sensitive to thermal changes and external impacts causing malfunctions
Solution Approach 1:
The patent changes the interaction mechanism from precise point contact to extended surface contact. The actuating element's engagement surface is designed to contact multiple points on the displacement element simultaneously, creating a tolerance zone that accommodates positioning variations without affecting shifting reliability
Solution Approach 2:
The engagement interface is segmented into multiple contact zones along the rotational path. Instead of requiring single-point precision, the system divides the engagement area into segments that can independently accommodate positioning errors, with at least one segment ensuring reliable engagement
2Measurement precision
If conventional actuating elements with fixed positioning are used, then positioning precision is maintained, but rubbing contacts occur during shifting causing rapid wear
Solution Approach 1:
The actuating element is designed with dynamic positioning capability, allowing it to adjust its position during the shifting process. This dynamic adjustment eliminates rubbing contacts by ensuring that the actuating element only contacts the displacement element at the precise moment of engagement, rather than maintaining continuous contact
Solution Approach 2:
The shifting process is optimized to complete the engagement and disengagement rapidly, skipping through the potential rubbing contact zone. The actuating element enters the engagement zone, completes the shifting action quickly, and exits before rubbing wear can occur
3Ease of operation
If Bowden cable actuation system is used for gear shifting, then ease of operation is improved, but thermal changes in cable length cause inaccuracies in actuating element positioning
Solution Approach 1:
The system incorporates self-compensation mechanisms where the actuating element automatically adjusts for cable length variations. The engagement geometry is designed so that minor positioning errors from thermal cable expansion are automatically corrected during the engagement process, with the tolerance zone absorbing these variations
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 solution enhances the precision and durability of the gear shifting process by allowing for accurate sector alignment and movement without the need for precise actuating element positioning, reducing wear and improving shifting efficiency while maintaining robustness against external influences.
Implementation Method 1
the actuating element can be held in a deflectable manner in the first and/or the second setting position, so that it is carried along and deflected by the displacement element during at least part of the changeover movement
Data Source
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AI summary
The invention relates to an actuation device for a manual transmission in particular of bicycles, comprising at least two wheel profiles, which can be electively gripped by a surrounding traction means, wherein the wheel profile (2) with the smallest diameter is undivided and at least one other wheel profile consists of at least two sectors (3) which can be adjusted independently of each other, which are designed to be electively displaced into the plane of alignment formed by the wheel profile (2) which has the smallest diameter or displaced out of the plane of alignment, and an actuating element (14) which is decoupled from the rotary movement of the wheel profiles and which can be adjusted, and thrust elements (4) which rotate together with the wheel profiles, wherein a thrust element (4) is associated with each sector (3), which thrust element interacts with the respective sector (3) in order to displace the sector (3) depending on the position of the thrust element (4) into the plane of alignment or out of the plane of alignment, wherein the actuating element (14) interacts with the thrust elements (4) in order to move the thrust elements (4) during rotation electively into a first and into a second position.