Bicycle Shifter Sensor Anticipates Gear Shifts
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Solution Overview
Problem
Existing bicycle shifter systems fail to anticipate gear shifts effectively, leading to late sensing and increased wear due to cable drag and binding during gear changes.
Innovation Solution
A shifter system with integrated sensors that detect initial inputs on levers, interrupting torque before actual movement occurs, utilizing a lash mechanism with a pin and pulley system to prevent initial movement from rotating the cable pulley, allowing for smoother shifts and reduced wear by anticipating gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cable motion sensing is used to detect gear shifts, then the system can monitor transmission changes, but the sensing occurs too late (after shift starts) and creates undesirable cable drag
Solution Approach 1:
The sensor detects the rider's shift input on the lever before the cable pulley moves and before the actual gear shift occurs. This preliminary detection allows the system to anticipate the shift event, enabling torque interruption before the cable begins to move, thereby eliminating cable drag and providing timely shift sensing.
Solution Approach 2:
The sensing function is extracted from the cable itself and placed directly on the lever through a separate sensor. This eliminates the need for the cable to move in order to sense the shift, removing the source of cable drag while providing accurate timing information about the rider's intent.
2Ease of operation
If torque is interrupted before gear shift, then shift smoothness is improved, but the mechanism for detecting initial input must be precise to avoid premature interruption
Solution Approach 1:
The sensor is positioned to detect the rider's input on the lever at the very beginning of the shift action, before the cable pulley moves. This preliminary detection provides accurate timing for torque interruption, ensuring it occurs at the optimal moment to maximize shift smoothness without being premature.
Solution Approach 2:
The sensor provides real-time feedback about the rider's lever input to the controller, which then timing the torque interruption. This feedback loop ensures that the torque is interrupted based on actual rider input rather than predetermined timing, improving both accuracy and smoothness.
Data Source
AI summary
A system is provided for shifting gears in a cycle. The shifter system includes a motor that delivers a torque to propel the cycle. A variable ratio transmission is coupled with the motor. A cable transmits movement to shift the variable ratio transmission. A cable pulley is connected with the cable and is rotated to move the cable. A lever is coupled with the cable pulley and imparts rotation to the cable pulley. A sensor is positioned to detect an initial input on the lever that does not rotate the cable pulley. A controller interrupts the torque from the motor in response to the initial input and prior to a shift in response to the transmission of movement by the cable.